Well, it's the internet, you can't fully convey intentions through text alone and there is actually a subset of people that do point out errors just to stroke their ego (or worse, they're confidently wrong about their sources and are talking out of their ass). I do wish that people would be more accepting of factchecking and similia (grammar errors are something that you absolutely can't point out without being lynched, and that makes me livid), but I can't really blame them too much when they aren't.