@helge There is significant overhead to run just one server, and even higher overhead if that server is mastodon or mastodon-like.
Comparatively: grouping users together on a single server is _very_ efficient from both a connection and cost standpoint, especially if they follow each other.
If you take that same network and you spread it between multiple servers you have orders of magnitude higher resource costs per user and there's basically no getting around that with the current architectures. Not even getting into individual administrative costs (time) per person.