Don't most blogging platforms have the option to email replies? In any case, I prefer a bit of friction in the comment process, since it discourages people from "shooting off" without thinking.
I've noticed with HN it's very swarm-like and transient these days. Comment following is also difficult without some thread control. At a minimum you need collapsible threads. Too much to read, don't bother, say something that's been said already - and add to the noise. Or have a bypassed dangling leaf comment.