"For example, in terms of attracting new users" - meaning that's the whole point of the question, so I'll address that.
Lemmy isn't a corporation and doesn't have to think like one. Market share means nothing. The goal is a high-quality app that does what its users want. If a majority of those users have a similar range of political views, that's just how it works out. There's nothing stopping ultra-conservatives from spinning up Lemmy instances if they want, blocking communities whose overall personality they don't like, and banning users they don't like. If this balkanizes the lemmy userverse, I don't see that as an issue.
Conversely though: you are considered a right-winger by some (Lemmy.World = neoliberal bastion of not extreme enough Leftists). (And to be extra clear: me as well:-)
I agree that we must exclude trolling behaviors and those who refuse to not do them, but not bc of their beliefs and rather bc of their intolerance to anyone who disagrees. But by the same token, we must not become them in the process.
This would exclude both the Alt-Right, as well as the Alt-Left, leaving us centrists in the middle. And a week ago I would have added: "who don't want to violently overthrow all of society", although now I'm not so sure that a goodly fraction of Lemmy agrees with that anymore.