It’s really nice that the Local feed exists, but when people just bulk subscribe to 8 different communities with the same name, stick to their subscription list, and then treat them all as the same place, that just kills a lot of potential for heterogeneity.

That's what people are used to from Reddit. They're used to having one giant subreddit about one topic. That's why everyone's centralized themselves on lemmy.world or kbin.social. That's why one of the most requested features is the ability to make "multireddits" (or otherwise combining all different communities into one)

This is a culture problem to solve, technical solutions can only do so much to help.