Also this part of your post makes me curious about a couple things
1) In my reading of the studies you linked on MAOI inhibitors - I saw no claims of "exponential" effects on nicotine addiction. My understanding of the reading was that both sets of rats continued to self administer nicotine (indicating addiction) but the MAOI inhibited rats administered more and more frequently. I did not see a conclusion as to the magnitude of the impact on the rats or on humans. Did I miss it?
2) If the MAOI inhibitors can cause the addiction to other substances as you indicate with chocolate, then would it not occur if a person smoked and ate chocolate at the same time as the MAOI inhibitors would be present with the chocolate? Would drinking coffee while smoking exponentially increase you addiction to caffeine? This seems to be what you are saying.
I am glad in your prior post, you can see what I am getting at

At no point did I suggest, or do I want to suggest, that one should encouraged into nicotine, sugar, caffiene or anything else that may or may not form a habit for people either, just for the record
I just want if possible, the vaping community to be clear that nicotine alone is less addictive than smoking, that nicotine is not the only or even primary reason why smoking is addictive, and few pages back, there was a bit of talk suggesting otherwise. So having just been over that already in the thread, I had to bring it up
1. The exponential effects I describe are more from my own understanding of mao inhibitors, as both an academic with a hobby interest in the brain, and as a former drug user. I have an very unusual level of understanding of such brain phenomena, both academically, and subjectively.
There are plenty of reports of people getting a real buzz from things like chocolate, when on prescription mao inhibitors like selegine (sp). I could post "reports" from users who have done this sort of thing, but it contravenes the forum policy here in a few ways, as well as the spirit of those rules. While its highly useful to vaguely talk about such things here for comparison, I will do so in such a way that avoids detail or specifics.
It's worth mentioning these pharmaceutical mao-i's seem typically a little stronger than the mao inhibiters in tobacco. However thats not to say, tobacco is not potentiating other pleasurable activities, as ill explain below.
The difference in terms of the rats behaviour in the studies was re-enforcement, which is what we often think of as addiction - that is to say, getting some, made them want more and more. Nicotine alone was pleasurable (or not unpleasurable) enough for them to want it in the first place, but not to adapt their behaviour in terms of learning to want more, ie, it was not significantly reinforcing. Thats really a key quality of addiction, tolerance, reinforcement and habituation. I don't think the studies would conclude that nicotine is not at all addictive, if that was their purpose (which it wasn't anyway), only that there are clear quantifiable differences in the nature of nicotine, versus nicotine and mao-i, especially it terms of reinforcement, that made the later more like hard illicit drugs, and the former not like hard illicit drugs.
This is partly where my comparison with being slightly more addictive than caffiene comes in. From these studies as well, but its also an educated guess based on its brain actions (as a nicotinic receptor agonist), and the subjective effects of nicotine only, which on the surface, lack the more stronger body pleasure qualities of smoking, and is more like a plain wakefulness stimulant.
For total honesty, objectively etc - There is some dose based variation in nicotines subjective qualties. At lower doses, it it is much more of a plain wakefulness stimulant, at quite high doses it begins to have some comparatively mild beta-endorphin qualities, as well as being stronger in its stimulant character.
Not even near as much as smoking etc, but for those seeking to avoid smoking, sometimes these higher doses can be a little more satisfying there (and such mild beta-endorphin effects with nicotine at higher doses are reported in the scientific literature too).
Although this might be slightly effective as an approach for those experiencing cravings or withdrawls from smoking, it is overly stimulating. As such, some low level of mao-inhibitors in the e-liquid would probably preferable from a health standpoint, even a nicotinic receptor tolerance standpoint, rather than very large amounts of nicotine, in people that require such large doses of nicotine in my personal opinion. That however is another discussion.
I think overall caffiene is not a bad comparison for nicotine, both in terms of health effects, and addiction, even if it is slightly more addictive, its overall character is indeed somewhat similar, for something that can be used as a well known example anyway.
2. As I stated above here, the mao inhibitors in tobacco combustion do not seem quite as strong as pharmaceutical ones. While they may increase enforcement to chocolate or to caffiene, they are not apparently strong enough to produce full blown drug like effects with these substances.
There are probably two reasons for this that I can think of, that this may in part be because those pleasure pathways already have tolerance from smoking (I dont doubt this is a factor, as it causes large variations in the subject effects of smoking, to the point where heavy smokers cease to notice any pleasure), but it will also be in part, for sure, due to the actual strength of the mao-i.
Its hard to quantify the exact differences. Studies in smokers suggest something like a constant 40-50% mao inhibition I beleive (just off the top of my head, id need to look it up), whereas some pharmaceutical products can induce up to a full inhibition. The exact effect of this on potentiation and subjective effects may also not be a 1 to 1 relationship, but some form of curve.
However, that said, it does seem that this mao-inhibition process with smoking plays into effects with other drugs, quite obviously in fact, in many ways that are familiar to smokers, and former smokers and society at large.
It enhances the pleasure associated with alcohol, sex, and food (also painkilling opiates, and other pleasure inducing drugs although most people wouldnt realise this, lol - still youll find mention of this link on the net).
To the point where strong conditioning exists around eating, drinking and copulation (and in those that use them, those other illicit activities) - producing a strong conditioned desire to smoke when those things occur.
We should all be quite culturally familiar with this, but until focusing on how the mao-i's enhance the pleasure of these also reinforcing activities, by flooding the brain with available neurotransmitter, we would not know why.
Well - this is the clear reason for that effect, and its associated conditioning.
It may also be apparent that smoking at these times feels subjectively more pleasurable. Again, this is the reason. Its worth noting that for opiate users, they feel an active increase in the effects of said drugs, when smoking. This is most likely broadly true, of a number of harder illicit drugs. With milder activities, like food or sex, all that is subjectively apparent is an overall increase in experienced pleasure, particularly from the smoking itself.
Again, these effects are probably lower due to tolerance, in the regular smoker. If a non smoker were to have their first smoke, during something that could be strongly potentiated - they would likely feel a very significant effect, possibly even one that is overwhelming.
Smoking probably does increase habituation with caffiene, and chocolate, just at a more subtle level, without producing full blow drug effects. I would certainly suspect this to be true, even if its too subtle for users to note a subjective difference beyond "this is nice" - the coffee and a smoke thing is fairly common, no?
Sorry to talk about smoking so much for those that read this! Remember, you ain't getting cancer, or heart disease or stroke and vaping tastes nice! (And theres no ash, lol)