"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.