That's the #1 risk to HN, so we worry about it. Like many here, we've seen it happen before, and HN was literally founded on the idea of not letting it happen again—or at least trying to stave it off.
That doesn't mean we don't get the value of hard-hitting technical critique done in a right context; it means that HN is not a right context for the shitting variety. Nor do we ask users to be namby-pamby milquetoasts; we ask them to understand enough about the fragility of the community to preserve it for the future. We don't want a scorched-earth outcome.
So go ahead and make clear technical criticisms, but make them without the extra jabs that people often feel compelled to stick in. That latter behavior isn't hard technical critique anyhow, just chest-beating.