There is still a lot of QQ around the community on thieves. To be honest I am also one of people who occasionally nerd rages about them. What is interesting, I dont actually think that thieves are OP. In fact I think thief is a middle of the pack class in terms of overall PvP contribution with the only aspect of the game where they are broken and probably a bit OP being WvW roaming.
Then again as I said, I keep getting thrown off balance after some encounters with thieves when I want to smash my proverbial keyboard. I think the reason of this is the fact that a thief class due to its specific can still make a winner out of a rather poor player. While in case of other professions getting any results with simple play will be much harder. Before you start sharpening your pitchforks, no I dont think or say that all or even most thieves are nabs. I encountered several skilled thieves during PvP and I acknowledged that in my in my post-fight chats with them. I can see when a thief is good and I know it. That being said, generally if a player performs rather poor, he is easily countered. Most of the times. This also applies to thieves in several cases. But due to how bursty and single-focused they sometimes are, they can still yeld results even with very minimal effort. For example I might be distracted by something for a moment, happen to have my stun breaker on cooldown or endurance depleted. What happens? BOOM! Backstab, heartseeker, heartseeker, heartseeker, shadow refuge, safestomp, win. This sort of playstyle requires very little effort and can still dominate even a very good player if you have a bit of luck. The same principle also applied to 100b warriors but in that case it was much more gimmicky and prone to failure if warrior missplaced the 100b wheres in case of the thief he can continue to spam and still end up victorious.
Thief class has some potential for a very spectacular and effective play. A bad thief player who only spams his 1,2,2,2,2 will probably not win a match. In fact he will not. He will also probably die often and be a liability for your team. Yet in the meantime he may still randomly gank some unsuspecting players (since that is what he tries to do most of time, at some point the “crits will align”). And those players may get really kittenhurt when they check the combat log and realize what the thief done to them (or rather, what he did not done). I know I do. I rage about eating a 8k HS even if we just stomped their team and won the match. This leads to hate on class which we can observe in community pretty much since the release of GW2. Meta and actual strenght of each profession will not change that. So as long as this issue prevails, I dont think that trying to prove that thief is not OP (becouse as I said, overall I dont think it is) will do any result. People will keep raging on thieves for exact reason I outlined above.