Because person X has all the best gear and is effective during endgame content when in a competent team lets nerf everyone.
There is defo an element of this going on, but there are real examples where a class is kicking more ass than it should or not enough as well.
This always happens in most games that have a level of MP like BF3 being a prime example of nerf's & counter nerf's then buffs and its all based off well someone did this so it must be OP, so i will make some noise on the forum to get it changed.
I have a sniper with 1213 Exp and some times in PVP i feel that if i could throw the weapon at them it would do more damage and i have good gear. But then the reverse must happen, when i down a low level in 3-4 shots, he must be thinking Sniper is OP,
To be honest, I would say my sniper is the most underpowered toon vs the gear on him, If you look at the negitives listed below for sniper you would think that would mean its single target DPS would be super high,
1) They cannot move and shot
2) They have cast time + distance + line of sight issues
3) You cannot take much damage,
You put that against any other DPS class & you would think they would hit the hardest but they don't,
I still play that one the most as i like the class, just means i need to play smart and work with the hand BW delt me + pray to Jebus that a healer worth his salt is healing me.