They're already banned—HN has never allowed bots or generated comments. If we have to, we'll add that explicitly to https://news.ycombinator.com/newsguidelines.html , but I'd say it already follows from the rules that are in there. We don't want canned responses from humans either! Edit: It's a bit hard to point to past explanations since the word "bots" appears in many contexts, but I did find these: https://news.yc…
It’ll be interesting if we soon come to a day when a comment can be suspected to be from a bot because it’s too coherent and smart!
Basically, if it improves thread quality, I'm for it, and if it degrades thread quality, we should throw the book at it. The nice thing about this position is that comment quality is a function of the comments themselves, and little else.