There are many benefits, and having many servers instead of one is the core idea to the Fediverse.

Instead of a single towering kingdom at the whim of a monarch like spez/Redditco, Zuckerberg and Musk that call all the shots, you have a bunch of dukes and duchesses each ruling their duchy, but as a user you get the freedom to where you feel most comfortable. Yes, admins of each Lemmy server can act like tyrants and tinpot dictators, but to establish the network, there has to be open dialogue between admins to establish what behaviour is acceptable across servers. Admins that don’t or can’t control their users are exiled (de-federated).

It’s also good for resilience: if you have a handful of accounts, and one of your servers go offline suddenly (from either random hardware/software issues, or a governmental takedown order), it doesn’t take all of Lemmy offline. I remember Redditors up in arms when its potato servers shit the bed.