There’s no real advantage to joining the largest instances, you can view all their content from your fediverse account regardless of which instances you’re on (unless it’s been defederated which only applies to a small number).
Too many users/ traffic can overload the servers reduce the experience for everyone. Instances are mostly hosted by individuals and becoming too large, too quickly could have a financial impact on the owner.
Additionally, if any instance ever gets too large a share of users on the fediverse, the way they operate and their rules become “the standard”. Then we’re basically back at Reddit.
Diversifying instances is good in the long run!
The only real advantage I can think of is the bigger instances will already have their “all” feeds more populated already. But you can still add any communities you want on smaller ones.
