One of the key differences between social media and a forum like this is - social media profiles are often (not always) about people who use their actual names. Whereas on a forum like this, folks often choose a screen name or handle for privacy.
This difference does effect what might be said and how it might be reacted to. On my social media, I'm careful, but I don't lie or deceive. Often if I come across something I don't like/agree with, I simply ignore it. Sometimes I might say something contrary if I think there's a chance that the person could possibly be receptive to it. And sometimes, things go too far and there are social consequences. Like being blocked. Or losing a friend. Not that that is always bad, since I no longer am tempted to look at their opinions.