Thanks for the explanation, Dan.
A tension of this site is that its core focus (intellectually interesting stories/discussions) makes for an interesing place for people to gather, giving rise to lots of additional opportunities to add value, e.g. connecting people who are interested in the same things. Some of those are very valuable! Helping people find mentors, for example.
Nevertheless, we're pretty rigorous about moderating this sort of thread out, because it's not the core focus of the site. HN's core focus is the goose that lays the golden eggs. Taking care of HN means taking care of the goose and (mostly) foregoing everything else.
To switch poultry metaphors, it's a case of Andrew Carnegie's line "Put all your eggs in one basket and watch that basket." [1] From that perspective, it's not great for HN to have threads that are lists of contact info, even though the contacts themselves have value.
Staying focused isn't fun. It means making unpopular decisions and seeming like we don't care about things we actually do care about. But over the years the moderation has stabilized to a bunch of standard practices and this is one of them. It definitely isn't personal or specific to a given post.