Centralized platforms are proprietary, brittle, easily targeted. When they are taken down, they stay down.
Lemmy is, effectively, a protocol, not a platform. Anyone can host an instance, and they all talk to each other by default. Any of the big instances get knocked down, and they get replaced by a dozen others. An instance may die, but so long as someone wants to put up another, Lemmy remains.
Bitcoin is not a centralized platform. Tor is not a centralized platform. Government has had little success targeting these protocols.