What is the appropriate number of times to "just move on and ignore" before finally deciding to say something because the integrity of hn as a platform is at risk?
The latter. There are two recent topics that ended in flagging and really low quality doscussions, no curiosity, no open mindedness and sometimes utter disregard of human rights: Caste based discrimination and the war in Gaza. The latter usually has "pro-Gaza" submissions flagged even faster than the former had for stuff critizing castes and caste based discrimination.
I am torn, in the one hand those discussions are often rightfully flagged for the coments themselves. On the other hand, this shows a general social development I don't like, especially since HN used to be, or at least is suppossed to be, a place where even hairy topics can be discussed. And I think the "tech" community at large would only benefi from multiple views on those subjects.
There are not multiple views on subjects, that part is subjective, per se. There is objective truth which this site is trying to prevent via flagging and other ways to limit discussions. The whole point around HN is about tech news etc. is BS, to me at least, as there is no way to disentangle anything from politics as we live in the world ruled and controlled by such interests.