You've never worked at a place where someone was an incompetent hanger-on who was an expert at self promotion and stealing credit? Or hired someone like that accidentally?

Notwithstanding, I have long argued that a non-profit credentialing body for SWEs offering cerification exams (which also required regular updates) akin to passing the bar or USMLE could go a long way to solving this problem. It would come with other drawbacks, perhaps not worth it, but we have to accept that constant tech interviews is the price we pay for refusal to standardize and professionalize.