Like for example rateyourmusic has a weighting system that basically means only active site users affect an album's displayed rating or chart position. It's also a site where moderation policies heavily discourage joke reviews and ratings, and users tend to care (usually a bit too much) about the ratings and chart positions of their favourite albums. I'd also say that rating biases on RYM tend to lean towards music that's at least a few years old and tastes trend a bit more niche than a lot of other platforms.
Compare this to letterboxd, a site that that is culturally and moderation-wise very amenable to the joke review format, although that usually doesn't play into the ratings too much. Charts still play a role here, but for the most part they take a backseat to the social functionality, and the focus tends to be more on what's new (makes total sense with how movies are released!). People here take averages pretty seriously but not to the extent that RYM users do imo.
Goodreads is kind of a black sheep in this crowd to my eye. While average book ratings are still displayed prominently the chart/ranking culture doesn't seem to be as strong and the site tilts a little more towards being a simple catalogueing service with social functions. Tastes here, in my experience, lean much newer and less niche than RYM, with letterboxd falling somewhere in the middle. Notably, the site demographic also skews a little bit older, more female, and for lack of a better term, less weird than the other sites.
I think those three websites kind of fall on a spectrum from most tryhard/enthusiast/hobbyist to most normal/low-key/casual and also from the most to least monocultural, although obviously in each case there's a wide diversity of how individuals use the site.
What does all of this mean? I don't really know! I think there's something to get at with how site design heavily influences culture, either through promoting certain behaviours in users or attracting users with certain patterns of behaviour. Mostly I just had these thoughts bouncing around that I wanted to put out into the World Wide Web. Feel free to comment if you have anything to add or if you think anything I said was off-base.
(P.S. I didn't mention glitchwave or backloggd because they mirror rym and letterboxd (respectively) in most of the ways I was addressing here. Glitchwave is developed by the same team as rym so it's unsurprising it exhibits a lot of the same design philosophy.)