My answer to this question has been quite controversial, attracting several hundred positive and negative votes and a long thread of comments. An initial batch of comments was moved to chat per the usual site policy, and two subsequent long streams of comments were simply deleted with no public announcement or explanation.
Many of the comments that were deleted were very thoughtful and interesting and, in my (possibly biased) opinion, contributed greatly to furthering the debate on OP’s question and related ethics questions. The deletion of the comments thus seems quite detrimental to a high-quality discussion and contrary to the goals of the site. It not only frustrates users who have thought and attention to writing good comments, but also (more importantly) deprives the community at large of important follow-up content.
A moderator who left me a chat comment explained that they “had to” delete the comments because comments can only be moved to chat once and the comments thread was “getting out of hand” (or words to that effect).
My question: what should be done about the comments associated with questions or answers that attract a lot of attention, including long streams of comments, many of which are of high quality and highly relevant to the debate, and which continue unabated long after the initial stream of comments has been moved to chat?
If your answer is that deleting subsequent comment streams as was done in this case is the best policy, please explain why you think this best serves the purpose of fostering the most informed and high-quality discussion possible (or why it serves some other, even more important, goal that I’m not thinking of).