I have loads of FB friends who I've never met in RL; many of us belong to a group set up for people in our line of work and some have become FB friends outside the group. Within the professional group some are in a position where they have a budget and are able to offer us work.
However, given the recent political cicrs, quite a lot of them like to make their views known in no uncertain terms.
I think it's really tactless because although I may disagree strongly with them, I don't want to get into a heated debate on FB or with someone who holds the purse strings in terms of my work.
I just can't believe people are so tactless to flaunt their politics on FB when they may offend other people who aren't just 'friends' they are also professionals in the same line of work.