“I agree that 'quality' can not be 'tested in'. But the approach you describe appears to go-ahead and attempt to do something just, if not more, difficult. You suggest that a programmer will produce quality work by just coding 'better'. While a skilled and experienced programmer is capable of producing high quality software, who will tell them when they don't or can't? We are all potentially victims of the Dunning–Kruger effect, and as such we need co-workers to help.
There are a host of biases that stop a programmer, product owner or project manager from questioning their work. The confirmation and congruence bias to name just two. These are magnified by group-think, and without the input of a more independent, experienced and skilled critical thinker, soon allow mistakes to occur.
Think of it this way, how do you know your products are good enough? how do you know they are not plagued by flaws? Flaws like: a message that tells me my payment method is invalid - before I've entered one or the absence of a scale on the iPhone maps app.”