Widespread popularity of drugs predates WWI, let alone postmodernism, which became popular (outside architecture) only after 1960s (mostly in 1970s).
He said that polls show the younger someone is, the more likely they are to support legalization, and this appears to be true. You can't explain that with anything going back to 1910.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one. (Immediately before; refresh the list-of-threads page before posting.)
3. Open Threads should be posted in Discussion, and not Main.
4. Open Threads should start on Monday, and end on Sunday.