I mean they are?

You can host an instance, and if the instance is doing something you don't like, you can certainly change it and prevent it from doing it. If the main Lemmy devs put stuff in most people don't like, the software will just get forked, and most instances will use the non-shitty version.

Lemmy is what the majority of users want it to be, since everyone can just start a competing site that's not suffering from the "outside-the-walled-garden" effect, with a different featureset. Users will move to the instance with the best featureset for themselves.