You're confusing "lemmy.world" with "Lemmy".

Lemmy itself doesn't "allow" or "remove" shit, because it's just software. lemmy.world is an instance (server) running that software; some people administrate lemmy.world, and they decide the rules of that place.

Other groups of people do the same. But their rules might be completely different. For example, this post is in a Lemmy instance called lemmy.dbzer0.com; the admins here have completely different views on what's OK or not to post here. Same deal in lemmy.ml, mander.xyz, sh.itjust.works, so goes on.

Later on you mentioned PieFed. PieFed is simply another software alternative to Lemmy. It won't "allow" or "remove" shit either, but instances running PieFed will.

Additionally, each instance has its own communities ("subreddits"). Each with their own moderators, that might decide on the local rules, as long as they don't contradict instance rules. For example, your comments were removed from !showerthoughts@lemmy.world and !unpopularopinion@lemmy.world because they were against the rules of those two communities, but I bet that if you posted the exact same things in !politicaldiscussion@lemmy.world instead, it would stay.

Side note: I hate with how they phrased that rule (no politics), but I do agree with the spirit of the rule, and the fact they removed your comments from those two communities. A lot of the Fediverse userbase is politically engaged; that's a great thing, but if you don't have at least some spaces reserved to talk about other stuff, everything becomes the same. Simply labelling it (like you propose) doesn't work because there are political aspects in everything, so the dividing line is really fuzzy.