I agree. Weed (etc.) can not be healthy "for fitting into normal, standard life".
But there is a different view to it, than just claiming "drugs are bad".
Because there are quite some people claiming, that a "normal, standard life" with a 9 to 5 job and bounded by many weird social customs in a hectic enviroment which very often rewards lying and assholeness - is in itself not healthy. And some drugs can enable people to step outside and see things from a different angle, that "normal" is maybe not allways good. And that a different "normal" might be possible.
The main problem arises if those people now decide to escape into the psychodelic world, instead of using their insights to actually do things differently. Most of them will mentally break down, sooner or later.
And btw. "If you take ten 16 yr olds, allow them to experiment" ... most 16 yr olds will experiment, whether you allow them, or not. Which I think is good in general, for progress for the new generation, but I think the chances are much higher for things go dark, if you push them too much into illegality. Then it is much harder to help them find moderation and balancing.
So I would argue, drugs can be and are beneficial for society to develop. But they are powerful and therefore dangerous.