It is not your or my job to inform new vapers of any thing with out the proof to back it up.
Imo flavors should have an ingredient label just like food labels. Then there wouldn't have to be this big to-do about any particular ingredient, especially since things will come up about other chems in the future. Just read the label and decide if you want to buy that flavor or not based on the current knowledge at the time.
It is also possible that future flavors will start containing POSITIVE ingredients a vapor might WANT. Ingredients that promote lung health, for example. Maybe eventually, even nanobots that reverse lung damage. Heck, one day there might be nanobot-infused diacetyl so you can have your custard and vape it too.

All the flavor, none of the risk. Seriously though, it can cut both ways. Ingredients don't have to be viewed as a nasty secret to hide, they can be flipped around as a marketing tool once vaping is embraced instead of demonized [by the gvt] as tobacco's evil cousin.
But disclosure is a positive thing. You walk into a grocery store and pick up a food item, and if it has corn syrup you may not buy it... but it does not have to say on the front: "CAUTION, CONTAINS CORN SYRUP!" Then you pick up its competition and maybe it's made with raw sugar instead or even Stevia... and that's the one you buy. Or if you like corn syrup, you get that one.
It's all about making an informed decision, but piece-mealing the chems is a mistake as we have already learned. First it was diacetyl... then the replacements AP/Acetonin were found to revert to diacetyl, so now those are on the poop list for some vapers ... (and btw, far fewer companies reveal acetonin than A/P or diacetyl). But remove all three of those from the equation and the chem used for a custard note is butyric acid... which happens to be an irritant when inhaled, as revealed by TFA on their site (even though they use it, obviously to avoid using the other stuff ppl are concerned about).
And frankly, while dicetyl never bothered me, butyric acid does. So now I want to avoid BA too.
FlavourArt tests for dicacetyl and A/P but no mention of acetonin or BA.... mycleanvape only sells liquids that are dicaetyl, A/P
and acetonin-free, but they don't mention BA, etc...
TFA happily mentions when a flavor contains ANY of these (which is why it's always been my go-to vendor)... but it just seems easier at this point to just list ALL ingredients and let vapers choose flavors based on those labels... or based on the flavor name and picture, if they don't care.
Frankly diacetyl felt much nicer to vape than any of its replacements (but then radiator fluid goes down easier than vodka so not saying this is proof of anything), so I wish a definitive study could be done with people, not animals. Many people would volunteer who already think it isn't a problem. And as many others have mentioned, you don't have to wait for serious lung disease to see damage is being done... there would be subtler changes much earlier that would be good enough evidence to avoid diacetyl, if that was the case.
In the meantime I am erring on the side of caution, not knowing if it's really a problem or not. I still think I exhale most of everything I inhale, which leaves little to be absorbed. But I am no scientist.
That's my nickel on it.