I think the issue isn’t that the Lemmy developers don’t want these things to exist that you’re talking about, so much as them being the only ones in a position to make the changes or accept the PRs to make them happen.
Lemmy maintainer here, and I’m really curious what gave you this idea. We generally welcome all contributions to the project. On the backend I made a pull request to add plugin support which is waiting for feedback. Onthe frontend I havent heard any interest in a plugin system yet.
So if this is something you want, you’re welcome to implement it and open a pull request.