Productivity tools need to be very careful about radical change. Especially when the change won’t make anyone more productive.
It's hard enough for people to hear criticism or fix mistakes without their head, or a colleague's head, being called for.
The rest of the GP comment was fine.
It's unlikely that the person in question is reading this HN thread, but there's a chance that they are, and that means we should do better.
Here's the thing: maybe we don't owe "a lead at a company as high profile at Slack" any better, but we owe ourselves better in order to have a decent community. That's what https://news.ycombinator.com/newsguidelines.html is about.