Very good article, as usual!

Some textual confusions though: how two last bullet points before the Conclusions are related to the feedback? The rest are about testing, but the last 2 ones are about developers. Do you mean someone should give feedback on developers as well?

If it's broader than all kinds of tests, then maybe code review can be added to the list as well?

Then also "the only way developers can be guarantee software or code works, is by testing it". In my mind testing can only guarantee software or code does not work. Acceptance testing can somewhat guarantee software is superficially ok to stakeholders. But correctness can't be proved by tests.

One more important skill is not mentioned. Recognizing problems, which has been solved already, and finding ready solutions (every thing else you said on consequences applies, of course).

Other than those two places this is something every technical manager should read.

The next question is then how to grow coders into software developers? Are there dumb developers who never grow or is it for everyone? Basically, the rest is psychological.