Earlier quoted context omitted.
I'm not sure I agree about necroposting. I find it tends to increase the noise level more than simply creating a new thread about the topic in some cases, as people see a post with tons of comments and don't realize that many of those comments are out of date and no longer accurate/relevant. There's obviously a line to draw somewhere. You don't want 50 posts on the same topic clogging the top of the feed, but zombie…
And completely unreasonable to me. Even on reddit the cutoff is... 6 months ? People not realizing that it's a necropost is either a failure of the poster not declaring it as such, or of the forum software - see how Discourse auto-highlights necroposting !
Good forum software makes it less of a sin, but that's pretty rare on the Internet. This isn't the Usenet where people's clients could be fully featured on every topic.