Unless you don’t vote on much, I think you underestimate how much information can be attained from the pure data of up/down votes.
There is also the fact that people traditionally vote on stuff they wouldn’t comment on because they see it as more private.
Crossposting is popular and there are a lot of overlapping communities that post the same sort of content so of course you will right now. The current lemmy users are overwhelmingly nerdy, so piracy and gaming communities are going to show up a lot and there are several of them over the different instances.
So you’ll see this on several gaming communities and again on several piracy communities.