This has been internet community stuff since internet, honestly. Small websites run by a dozen school friends can wind up with this. Reddit, from my understanding, was always rife with it.

The decentralized nature of Lemmy means a lot of people curating their own communities. Walled gardens are a feature, not a bug. As long as the federation aspects are held together the ecosystem can self correct by letting those communities isolate, either internally or externally.

Just try not to take the walls personally, even when they are. We all run into them sometimes.