Why is there such a disdain for the COD guns in CS:GO? I love the SG!

People find that "noobs" use them too often, and sometimes they can be far too OP, or at least in some peoples opinions.
The SG, as far as I know, it has the best AP in the game and is very good at picking off people from both close by and long range. People are just jealous that "noobs" can use them and get more kills than them. IDK, use whatever guns you want. I honestly couldn't give a flying fuck about anyone saying I'm trash for using a gun that's in the game for a reason.