It's definitely a good thing. If someone wants to be on the popular platform go back to Reddit or Twitter. That's what most people want. The Fediverse is the minority that wants something different.
I think a lot of people would like the idea of decentralized social media in principle but most of them just want to download an app on their iPhone and get going instead of learning anything.
You'd typically think the abuse that happens on a higher level than dumb spam which those platforms succumb to would be even worse, but I feel we're somehow in a slightly better position to regulate that on Lemmy because of the delegation of moderation to users rather than instance admins.
We "just" need a relatively small amount of the "right" people to effectively counter that.
Their success is relatively easy to measure objectively by their effectiveness at protecting communities from i.e. subtle trolls or troll enablers.
Though one's opinion on topics can influence the ability to spot such scum in the moment, the "right" people/a good moderator will know how to do that despite their topical (dis)agreements.