besides the whole decentralised nature which is a plus anyway
Fun until you realize that other instances can block other big instances from accessing them. Ex. Beehaw defederated lemmy.world: https://beehaw.org/post/567170
And sadly for mainstream users, federation is too complicated compared to single instance :/
"my eyes" https://media.giphy.com/media/yhLV2DGTLDRCw/giphy.gif