I agree with all of this, except I will add that having a "QA Infrastructure" team does make sense. This team should not be responsible for product testing, but

I agree with all of this, except I will add that having a "QA Infrastructure" team does make sense. This team should not be responsible for product testing, but for building the cross-team infra and tooling needed to make it easier for the product engineers to write integration/functional tests. Of course, this is only needed once a company is above a certain size.