Yea. For example, the Paladin tank in the guild I just left had 2 piece tier 9, and the rest Ulduar gear... 43k hp 10man buffed. He's horrible. He's the most situationally unaware player I've ever seen. He can mess up on the same thing 10 times, and wouldn't change how he does it until somebody bitches at him. He's also like 15. I wanted to kill him through vent every time I was in a raid.
But, on the flip side, a fresh 80 in horrible gear, no matter what class, should probably not be in Ulduar 25, no matter his skill. He'd just be getting carried - unless the raid is fine with that, which is an entirely possible thing now that everyone just does insane damage.
I think we've talked about this before, though