The Internet brings out the best in some folks and the worst in others. It all depends on what is in the individual user's heart to start with, really. You're seeing people without their veneer of social acceptability in place.
When we meet people face to face, we are often more courteous just because we can be seen. Many people put a high value on others' opinions of them, so they try harder to make a good impression. Because they think no one knows them online, many people take the opportunity to be rude -- or at least not to behave graciously.
We humans are a fallen sinful lot, really. Most of us try to cover it, but our sinful nature ends up showing when we think no one is looking at us.
If you receive rude (or non-answer) responses here, please report every single one of them. It really isn't allowed. This is a user-moderated site, so all users need to be responsible to report any violations they see. If you're the user who sees it, you're the user who should report it.