But moderation of centralised social media is usually done by paid workers. Subreddits are not independent forums; Reddit admins interfere all the time, and they're hosted on Reddit servers so ultimately are at the mercy of Reddit's decisions.
I don't think Wikipedia contributions are comparable to subreddit moderation. Moderation is known for being traumatising work (see: lawsuits from global south workers over PTSD from seeing CSAM, snuff, and other traumatising content when doing underpaid moderation work) and I don't think there are many moderators who do it for fun. They may do it voluntarily because they like a community or think their subreddit/forum is a valuable resource they want to maintain. But not because the labour of moderation itself is fun. Meanwhile I imagine most Wikipedia contributors do so because they are interested in the topic, and it's far less likely to expose editors to traumatising content.