... A lot of the discussion was instructive, and a lot wasn't...
Which it the cost and benefit of free speech. You can't just get the good part all the time. As Marilyn (that would be Monroe, for the Millennials) would say: “if you can't handle me at my worst, then you sure as hell don't deserve me at my best.”
... it's not as if there is a shortage of places to discuss these things.
Like where?
Where else I can discuss such things not with total, mostly anonymous strangers, but with real people who I got to know over the years reasonably well, from their photography, to their musings and writings about photography, from their professional history to their family history, forming a pretty good idea of who they are, and forming a respect for what they did in their life and with their life? Those are the people I am willing to listen to, engage with, exchange opinions, even if we disagree (especially if we disagree). And stay friends even if we politely disagree. Those who can not disagree politely, should be banned and the offending post removed. Not the thread.
If it was not clear from the above, I am strongly against removing whole threads and banning certain subjects.