That's not really the case. The average strength people vape when they start is 18-24. Some higher and some lower. What may be too strong for you is what another person needs to get off cigs. What you vape may not be enough to get someone off cigs.
There are people on here that smoked 50-60 years. A person needs the nicotine strenth that gets them off cigs. That is unique to each individual.
There is nothing in your post that is false, however, it is not exactly the whole truth either. With the gap in information, it is a little misleading and can be confusing to someone who is new to this industry.
You are correct in the fact that different people have different needs, however, anyone who would recommend 18-24mg's to someone who smokes ultralight cigarettes, is either irresponsible or ignorant. Someone who smokes 5 packs of ultralights a day will need more nicotine than the person who smokes one pack of lights a day, but that does not mean they should take the daily requirements in one puff. Different people do need different levels, but when 24mg's is hurting and making you cough, your level is obviously too high.
FYI, the amount of time that you have smoked does not tell you how much nicotine you need. What size of cigarette (full flavor, light, etc.) does not help you determine the nicotine level needed either. It simply helps you figure out the level of throat hit to start with. This is why many manufactures label there products as low/none, med, high, extra high (0/4mg,10/13mg, 16/18mg, 22/24mg). How long you have smoked and how many packs/puffs you actually take will determine the amount of E-liquid you will consume, per day. Just because you smoked 500 puffs a day, does not mean you should get the highest dose available. Again the dosage should be where it is most comfortable for you.
While I am new to this site, I am not new to this industry. I have toured many factories and owned Ruyan stock before they were out of China and it became Dragonite. I was vaping before you could buy this technology, outside of China. There are many companies who operate in an ethical fashion and there are just as many who are only concerned with making a buck or just down right ignorant.