By calling other people pretentious doesn't that make you infact pretentious?
Not at all. Impressions of people has nothing to do with assumed knowledge 'n stuff. Everyone makes impressions of people whether it be polar or neutral. To say they are pretentious for relying on impressions is like assuming that they have a more "valid" experience of a person.
But yeah, people are being super pretentious. It's why I don't come to coding help as much as possible, because most people here just want you to be a major brownnose in order to receive "what help you are worthy of receiving." At least that's most of my experiences here.