If all someone cares about is convenience, why not just stay on Twitter? Why come to a decentralised network and demand that it centralise? It's like going to a vegetarian restaurant and complaining they don't serve meat.
The solution isn't "choose a larger instance", the solution is to discover people you follow through many different methods: https://fedi.tips/how-do-i-find-accounts-to-follow-on-mastodon-and-the-fediverse-how-do-i-find-my-friends/
And for admins, the solution is to use hashtag/instance relays: https://fedi.tips/using-relays-to-quickly-expand-a-servers-view-of-the-fediverse/