That is nonsense, I smoke daily since 16 years with also breaks of 2 years and shorter periods of 6-12 months in between. Sure if you didn't smoke for a while (or long time), you will get high instantly just as you likely get drunk after only 2 glasses of wine. But once you have your 'base level' again, nothing really changes after how much or how strong it needs to be to get the same effect. Same as with alcohol, you might be able to drink X more but that's it.
You describe some extremely rare cases of a serious hardcore level rasta pothead, like snoop dog, who would really not be cool with anything much less than his grade weed. Even then, he would be just fine without any withdrawal issues in the average Thai dispensary, even he might hate it. Changes the brain chemistry? Ehh ok, I guess many things do that, including social media usage of 12 hours average among Thais.
The difference as always is between use & abuse. And for some people weed doesn't work, for others it does. Same as some only drink beer, while others only drink wine, and others only hard liquor. While the one drinking beer would be going bad on hard liquor, the one drinking it thrives on that and gets sleepy on beer etc etc etc. Idiot people are the ones whining doing something they don't, to protect their own insecure choices.