It's not so much a Shakespearean "to have a QA team or not ...", but responsibility and accountability.
SWEs must produce unit testing because they know the code best. Dumping this responsibility onto QA is slow, evil, and wrong like quality control only vs. QA+QC.
QA teams must have the authority to ensure complicated code gets unit testing code coverage.
QA teams should provide partial and full-up integration tools and testing with the support of SWEs.
QA teams must have stop-the-assembly-line authority to ensure quality and testing requirements are met.
QA teams (or tools teams that support multiple QA teams) must make testing faster and more efficient.
There ought to be a suite of smoke tests such that untested code cannot be committed to the "production" branch, whatever that looks like, except in rare extreme emergencies.
All production-ready commits should be squashed, signed-off by another SWE, and have a test plan.
Test plans should be auto-generated, wherever possible.
Tests combined with test infrastructure should be able to be added to auto-bisect/blame breakage
Which tests must run and pass to accept a production proposed diff should be auto-minimized to those that touch particular area(s) and their precise-as-possible-but-still-correct dependencies.
Other areas that must not be neglected and shoveled onto SWEs: product management, UAT, UX, and operations.
I am a CTO and have always tried to have the QA team to be part of the Product Office (CPO) . It tends to keep us honest and ultimately it aligns the decision of churning out new features and building crap in the same team/person.
Now, don't get me wrong, my teams always do unit and integration testing, along with automation of those two. Devs are responsible for the quality of their work. But ultimately it os the product team, with input from their QA team the ones deciding if a new feature is ready for release as it is, or needs more polish
SWEs must produce unit testing because they know the code best. Dumping this responsibility onto QA is slow, evil, and wrong like quality control only vs. QA+QC.
QA teams must have the authority to ensure complicated code gets unit testing code coverage.
QA teams should provide partial and full-up integration tools and testing with the support of SWEs.
QA teams must have stop-the-assembly-line authority to ensure quality and testing requirements are met.
QA teams (or tools teams that support multiple QA teams) must make testing faster and more efficient.
There ought to be a suite of smoke tests such that untested code cannot be committed to the "production" branch, whatever that looks like, except in rare extreme emergencies.
All production-ready commits should be squashed, signed-off by another SWE, and have a test plan.
Test plans should be auto-generated, wherever possible.
Tests combined with test infrastructure should be able to be added to auto-bisect/blame breakage
Which tests must run and pass to accept a production proposed diff should be auto-minimized to those that touch particular area(s) and their precise-as-possible-but-still-correct dependencies.
Other areas that must not be neglected and shoveled onto SWEs: product management, UAT, UX, and operations.