Has it? I put it to you that the OP and resulting thread is a good example of a far more troubling trend of left-most progressive ideology.
It’s been a long and winding thread, but my take on it is that with a few exceptions of genuine conservative opinion from posters like @Sam_Stone, mostly this has been another painful display of progressive puritanism. Much of what has been posted is what I recognize as zealotry from progressive posters telling other liberal posters that their views fail the progressive litmus test, followed by accusations of bigotry for daring to challenge certain progressive views.
And even though there are very few progressive position with which I disagree, I find the dogmatism and intolerance expressed by some of my fellow progressives to be troubling because it is so clearly a mirror image of the intolerance and mischaracterization we typically find exercised by the extreme right - which is what the OP’s griping about. As a way of example: I did not imagine that posters like @YWTF, @monstro, could possibly be mistaken for anything but liberal, and often very progressive. Nevertheless, they have been labeled bigots simply because of their failure to agree with a handful of vocal trans-advocates on a very narrow set of trans issues. Posters like @DemonTree is being lumped in with them in a post just a few hours up-thread. While I disagree with this posters about some positions, I just don’t know how she can be reasonably accused of being illiberal or bigoted based on the opinions I’ve seen expressed to date. Even a poster like @ZosterSandstorm, with whom I’ve had disagreements, strikes me at worst, as a typical (be it abrasive) moderate democrat. If we can’t tolerate their views, and resort to calling them bigots, what hope is there for liberalism, let alone retaining (progressive approved!) conservative voices?
I think that if this thread’s “thesis” has proven anything it is that some posters here aren’t satisfied to simply jettison conservatives from the boards, they want to out, shame and drive away those who are not sufficiently progressive.