Maybe it's because I don't like monster of the week political drama, but I still don't see a reason to use them instead of Tumblr, Pinterest, or even TikTok.
That's why I mostly use Lemmy/Piefed because everything is neatly organized into communities that you can subscribe to. I mostly browse tech & gaming communities and my feed is very chill.
I wish that were also my experience with Lemmy. Even the communities and posts not focused on American politics are often about American politics. Discussion quickly devolves into some pretty extreme (and often violent) leftwing American political rhetoric. I understand Piefed can block whole instances, so maybe I should try that before I give up.
It really depends on who you follow. Almost all the talk I see is tagged with #uspol so I could easily filter it out, but even without it, it's not the dominating topic.
* Usually spoilered with "${local_country_code}POL"