I think the algorithms affect perceptions quite a lot. Sure, people on legacy social media (LSM) get to choose who they follow, what they like + retweet, but ultimately it is the platform's algorithm that dictates overall boundary in which those actions take place.
Interesting that you see the "echo chamber" or "CULT" as a bad thing as I'm finding that cyber cult formation is a lot harder to do on LSM like X. Not sure if you're still on LSM but many people complain that they suddenly find that X randomly unfollows people and deliberately doesn't show people that they prefer on the timeline (happens to me frequently). Like LSM deliberately makes it harder to form a tribe or "cyber cult" and prefers for people to just follow + interact with big name influencers. That's what I think nostr can address and fix.
Good point on Nostr clients having covert censorship. This needs to be fought against before nostr just turns into another LSM app.