This is honestly the only major issue I have with the Fediverse. Most of my Reddit/social media posts are related to three or so niche interests. My first Mastodon account was on the central hub for one interest that later defederated with the central hub for another interest. Not being able to interact with 1/3rd of the people I want to interact with just defeats the whole point of joining these kinds of platforms. Moderators just carving out a chunk of the Fediverse for their users is just unacceptable.