I get the idea of instances, like you can make your own and this is good for privacy. But some lemmy instances are much more popular and this in fact makes it another Reddit. If there are separate instances for niche topics, why not make it another community inside a larger instance?
You don’t seem to be getting an actual answer to your question, so I’ll try. IMO it’s the idea of being the master of your own domain and being in control; basically being an admin. If you want to be on an instance designed to your own preferences, like which instances it federates with and what communities you want to host, then the ultimate way to do it is to create and host your own instance.
I think you missed the start of the conversation ;) I host my own single-user instance on my own domain, and I was wondering why one (another user) would even think about selfhosting when the fact that it ties their lemmy identity to their server and domain made them not want to selfhost.