ATP is a wonderful social medium for gardeners and plant lovers, where you can easily get into discussions in those topics without appearing nerdy. My friends who are not into plants just look blank and you feel they do not comprehend anything you will say if you discuss further. At least here, we have similar interests. Some get carried away discussing other matters as well, but that is social interaction, just have to learn to tow down our thoughts as we type our comments.
As for FB, I have our account, mostly to keep in touch with my family overseas, and I have strict timeline privacy modes, so we are unsearchable, and I do not allow anyone to just freely post on our timeline without my approval first. Some people do not have the discipline and manners when posting. I only add those that I want to add, and pretty much I just post about my plants
At times, I know there are other people who are in a different phase in their lives, just gauging it from their own postings in their pages, and helps them find some outlet of sorts to read FB pages of friends. I don't play games in FB either, and I have blocked people too, so I do not see their postings. I also unfollow a friend's page, but still remain friends. Got to keep your virtual distance there too. Too much familiarity will breed contempt, and it goes with any other form of social forums.