I have felt that there have been harsh remarks made to people also. I'm not sure if it that the "reader" may be insecure about something and is taking what the poster wrote to mean something harmful, or if the poster just isn't relaying or thinking about how their words may or may not be perceived. My guess is a bit of both.
The bad thing about the written word is that it is difficult to express what it is exactly that needs to be conveyed. Either you will end up sounding too technical (a business letter format almost, as mine, I'm sure is reading that way), or you will end up sounding too vague, and possibly implying emotions which are not necessarily true.
What is written might imply a snarky, rude, or snobbish, attitude or emotion, but the poster might not have meant it to read that way.
Try not to take anyone's comments on the Internet too seriously. An imporperly worded sentence can and does imply an unintentional attitude or emotion which isn't there.
I am trying to be diplomatic in explaining what it could be. But then again, there are mean people in this world, and no amount of anonymity on the Internet can hide that.