While QA is important, none of these things increase code quality. Developers need to be writing tests as they code as a way of creating a good design. Unfortunately, most organizations are resistant to giving developers time to do this, even if they're willing (most developers also don't see the value in it, unfortunately).

IMO, a good QA engineer needs to be a much better coder than a regular developer--writing reliable e2e tests can often feel like black magic, and often the tester needs to understand what the underlying code does as well. Often the people who can do it, won't do it, because they have to fight organizations to do it.