Because instances defederate with each other. For instance Lemmy.world and beehaw.org defederated with each other. There is also the chance that the instance you are on might go under or close which means you would lose your account. So it’s not a bad idea to have multiple accounts on different instances.

Also, when one instance is overwhelmed or down for maintenance you can browse another.

Well, people might still want different accounts for different “interests” 😒

Right now, you can switch between accounts but it takes 3-4 clicks. I miss the hold-and-switch from Apollo.

Maybe because your instance defederated???