I include scare quotes only because as a topic, it’s so often misconstrued. It was supposed to be the intellectual solution but I think you really got to the heart of it — a need to accept people without mapping them into a normative culture. Any normative culture.
I went to college in the 90s and it was a big topic. Then it seemed to disappear from the radar screen like it was a solved problem though it’s not really a problem to be solved. It occasionally comes back when normative culture feels threatened and they want to appear open-minded.
It was about understanding and an appreciation of how different cultures do the same things (eat/dine, talk, celebrate, mourn, etc.) differently so you don’t need to map them into your culture to appreciate the other person.
At school, there were many emotional discussions because people felt they weren’t being heard or accepted. People in the normative culture appeared to feel threatened by the lack of conformance.
To various degrees, for survival, immigrants have always had to conform to the normative culture. It’s a wise move. But tolerance and understanding is a two-way street and culture is made through understanding and adoption. Culture is alive and old at the same time and I very much appreciate how you described it.