I think that to say developers should not be interest or responsible for quality is most certainly a cop out, there can and should be a level of pride of workmanship that is focused on the customer.

The main challenge with software is the possibility of unexpected regression in areas that are non-obvious when implementing a given feature. One of the more scalable ways of catching these regressions is via some sort of automated testing. I think that a QA support team can provide the tools and support that allow for teams to easily add end to end testing, which is vitally important when build large distributed software.

If the QA team is responsible for testing every feature from many teams there is definite risk of bus factor and finger pointing.

In the super ideal world the testing is specified via something like Cucumber and the orginal author could be the product owner with feedback from the engineer as he works to that specification. But I have never seen this though have heard it can happen, rarely.