When I was younger I learned so much and established many valuable relationships by having discussions on public services/websites. Many legends in the field were quite accessible on public sites and mailing lists. My life would be much worse if I hadn't had those experiences and it feels like a lot of younger people that don't have connections to the SV bubble are now going to miss out on similar experiences.
This isn't to say that we should be tolerant of everything but it definitely feels like we've swung too far in the opposite direction.
I'm a pretty active person online and I genuinely do not understand your concern. If you want to say something controversial online, just do so anonymously like you are doing now. If you want to give somebody candid advice I'm not sure why you'd do that in public anyways.
> Wasn't most "legitimate discussion" already happening in private already?
Probably, but I think there was still much more interesting discussion going on publicly in years past. It's anecdotal but I've definitely seen a huge spike in how many of my colleagues are retreating entirely to private communities and most of them never make public comments anymore. That's disappointing to me because I think there's a lot of value in having these discussions in the open with respected and accomplished names attached. It also gives a level of perceived accessibility that I think is important.