Didnt read the article yet but Im guessing 2 reasons: 1. because thinking for yourself instead of blindly believing in propaganda started becoming popular recently.
2. Theres no money in drugs that cant easily get millions addicted like alcohol and tobacco
They touch on it with the point that alcohol and other drugs make you feel good, but i think there are other practical reasons:
Psychedelics take a lot of time, usually at least a few hours up to days. Yes you can smoke dmt and it's only ~15 minutes, but it's not very convenient or socially accaptable to pull out the pipe for it (this might be changing with dmt vapes)
more work needs to be done to ensure the experience is safe
they're not super easy to find, especially not safely. I'd be interested to see stats like the one highlighted in the article for other illegal drugs
they're not chemically addictive
they don't seem to directly/reliably enhance productivity (e.g. caffeine or nicotine), socially lubricate (e.g. alcohol), or chill you out (e.g. weed)