The issue is that users generally don't get a say. Even in the fediverse, moderators aren't chosen democratically. Yeah, you can start your own community and try to build it up, but inertia is not in your favor.

Anyway, my point is that a "no politics" rule is not really reasonable. You can have one, and you can enforce it however you want. It will always just end up causing issues though. For example: look up Nazi degenerate art. It's just art, right? However, to them it was political, and it was political in a way they didn't like, so they removed it from society.

No moderator is perfect. Even if you trust them, blurry rules probably aren't the best. There's better ways to define the intent than "no politics" that create clear borders of what's allowed and what isn't. Blurry rules are usually best for those who want to abuse it.