The function of adjectives is to modify nouns. Nouns that modify nouns, in this particular context, are adjectives.

So a noun is a noun, unless its function changes and then the noun is an adjective. I think I've got that. But the noun in question, diaspora, does not function like other adjectives. So maybe some adjectives are more adjectivy than others.

Wanna take this outside?

Sure, I'll meet you outside. If I'm not there in a couple of minutes, you can start without me.