While it might be the case for some, calling them "people with problems," socially awkward or selfish (can't it be called selfish to rant that people aren't interested in chatting with you?) in general isn't going to convince anyone to start doing it. If anything it could make some willing to not care about doing it now.
That aside, people can have dozens of reasons to not care about party chat, unless something is going wrong. They could be in whispers, in chat with their guild, chatting in voice on Discord. They could be wanting to be efficient and chit-chat gets in the way. They might not understand English at all and leave chatting for people with the same language they know. And they might simply just want to finish the dungeon and move on to the next thing, not make friends. They're just temporary allies, not acquaintances, not soon-to-be buddies.
There's nothing wrong at all in any of that, and it isn't something only in our servers or World of Warcraft. This happens in every online game I've played for the last decades that had any sort of random grouping system. A hello at the start, a nice work (or recently "gg") at the end, and everyone goes their own way. If the group clicked well, some might add each others to their friends list and group again, eventually growing into chit-chatting, but that isn't something that should be taken for expected, much less for granted.