Welcome to the internet. Where you can be rude and not stand in front of the person your being rude to.
You forget after a wile the little things in any game that at first were difficult. So when you see a new player doing the same wrong things because they are learning as well, you poke fun. Some people poke fun because they are admitting that they were their once as well, and it's an attempt to co-misserate. Other are just rude, small minded jerks.
The trick is to never let it bother you, and learn what ever tasks you need to for you to become competent. Video games and real life. Someone is always gonna be the "New guy". And when your not the new guy, your job is to help the new guy. Because it will lessen the annoyance of everyone. Too many people forget that.