After mostly using Reddit for a while I realized that Facebook wasn't designed for having actual conversations or expressing yourself.
So for example, unlike sites like Reddit or HN, you can't downvote on Facebook. Downvoting is crucial so that the community can curate the content. Facebook (or Twitter) doesn't want you doing that. They just want as much content as possible and only care about likes/upvotes to trigger dopamine bursts. "Jane has liked your photo!!!" In anonymous sites people will just downvote you and tell you why you are wrong without mercy.
Another example. In Reddit and HN you have enough space for having actual conversations. In Facebook not only the space for comments is extremely small, but it's very difficult to know how are comments related to each other. After a couple of replies the UI stops making any sense. You don't know who is replying to who, etc. In practice, Facebook comments end up encouraging people leaving reactions to some content the user posted instead of being a place for discussion. Again, to trigger that dopamine burst when someone says something in the photo you just posted.
Of course, the objective of all this behavior shaping is to get more user engagement so that they spend more time in the platform and consume more ads.