Never blame QA; they have next no power over decisions and can potentially be fired for voicing anything that resembles an opinion. They aren't even allowed to use the word "should" in a bug because it implies that they know how the game is supposed to work, because as far as the Devs are concerned QA is nothing but a group of monkeys with minimal training to pick bugs and they are treated as such. They can't really fight back if a dev decides that a bug isn't worth fixing.
I think what you mean to say is that
testers are rarely to blame for buggy software because testers usually find the problems and have no real institutional power to encourage resolving them. Which is true. However, whether we should blame quality assurance itself for buggy software, in games or anywhere else, is a more subtly tricky question. QA in most software companies has a manager, who reports to someone else in production, who reports to someone else. The notion that all of *these* people are institutionally powerless to prevent buggy software can be true but is also specious. They have a specific job to do. Testers are hired to test: anything else including promoting fixes would be nice, but also beyond their job description. But the guy in actual charge of quality assurance, he has a job of ensuring quality. He can no more claim he has no institutional power to actually do his job correctly than the CFO can claim the company institutionally forced them to cook the books. As a professional, you can demand to have the institutional latitude to do your job correctly, or you can quit. But what you can't do legitimately is do a half-assed job and shirk all responsibility for the result because of extenuating factors.
I understand that people need jobs, and few people are actually in a position to walk away from one where they are not allowed to do it properly. But even so, you cannot claim the system is responsible and not yourself, when you voluntarily choose to act as part of that system. Testers don't explicitly have the responsibility to see that bugs are fixed: they have a responsibility to find bugs. But QA as a whole *does* have that responsibility, and its generally vested in people who do have the power to fight for fixes, and have a professional obligation to win those fights.