Are all these thousands of lemmy servers useless?

Correct me if I'm wrong. I read ActivityPub standards and dug a little into lemmy sources to understand how federation works. And I'm a bit disappointed. Every server just has a cache and the ability to fetch something from another known server. So if you start your own instance, there is no profit for the whole network until you have a significant piece of auditory (e.g. private instances or servers with no users). Are there any "balancers" to utilize these empty instances? Should we promote (or create in the first place) a way how to passively help lemmy with such fast growth?