That wasn't against the rules for the longest time, and people abused the hell out of it. There were (and still are, sadly) subreddits devoted to digging up comments they disagreed with and downvoting them, shaming them, and sending them hate mail. But even on regular subreddits, there were problems with meta content causing drama and downvote brigades.

The site would be better off with an outright ban on meta content.

Aside from one or two outliers like DepthHub, most instances of someone on reddit linking to something on reddit are a variation on "Hey, look at this stupid thing this person did, let's all point and laugh at how stupid they are".

/r/bestof would disagree with you.

I think hn needs a concept like r/bestof. It's the only way I get to find the really good user content in Reddit. There's no way I'd see most of that stuff otherwise.

In fact the main reason I read hn comments is the hope of finding comment gems posted by an expert in the field, someone with a unique perspective on an issue, or someone with a heretical but plausible idea.

Only in name, rather than action. Bestof basically functions as a massive sanctioned voting brigade.

(and I did mention outliers)

That rule absolutely needs to exist. Harmony through balkanization.

You don't get it if you haven't experienced how tiresome it is to see long-running subcultural feuds shitting up whatever conversation you'd like to be having.