It was my attempt at snark, though my statement could be considered in two ways; that it's bad, or that it's irrelevant. I agree with you. People are self-selecting, especially with social groups, and always have been. To me, the problems aren't like-minded people gathering, but people being disrespectful and hijacking groups for their own purposes. In 2016, I quit several Facebook groups when they were taken over by a minority of very vocal extremists. Even the most light-hearted discussions were all to often turned vitriolic by these agitators. (It strikes me that, generally, the people accusing others of group-think, are the ones preventing genuine debate over controversial issues.) (To paraphrase someone else, somewhere else; isn't it odd that you can have two people agree on 99% of things, yet won't speak to each other because they are polar opposites on 1%.)