I think you are missing a big piece of the bigger picture.
Much of the ‘utility’ of the lemmy alternatives is the significantly larger user base, which is what’s necessary for more niche communities to get off the ground and actually be viable. Without that userbase, lemmy is just another alternate place to discuss the basest common topics, that can be discussed anywhere. I mean, technology and news are nice to have, but it’s the variety of the niche community that are what keep people still hooked on reddit.
So in the end, making a place popular for the sake of popularity actually does serve an important purpose.