Mainly A term used in CS - Counter Strike, by noobs - low to mid skilled players that don't have the experience of killing AWPers, so they complain/ kick people for using the weapon or ban the weapon of the server.
Other weapons - Main Rifles (M4/AK) are as good as the AWP. Both AWP and main rifles have advantages and disadvantages and have strengths and weaknesses in different situations .
Of course at a lower Level of Skill (low-Mid) playing against similar skill level players, might give you a lot of Advantage using the awp, at higher skill level this is not the case.
But the reality is that in CS (public servers) it's better to practice your AWP skills and ignore people complaining, then using other weapons and getting accused and banned for cheating.
"CHEATER, WH, NOOB, AWP WHORE" - Just ignore it or you'll end up waisting your time arguing. Have fun and train hard.