I don’t necessarily need to know anyone on Fedi to enjoy using these platforms.

That depends what you use it for.

On Twitter I followed a lot of specialists in my field. On Reddit there were a lot of (anonymous) specialists in my field. Both were an important part of my working life, and it took two networks totalling ~half a billion people to deliver those few hundred people who made it so useful for me.

And that was also true for my niche hobbies and my niche leisure reading.

Small networks work well for some things. But not all things.