Right, I think some people honestly think that software just magically leaps from developers’ fingertips onto store shelves. Product management, project management, operations, marketing, legal, sales, BD? They just sit in meetings and play Candy Crush all day...
I never claimed that everybody but software engineers are useless, I wrote that managers are mostly useless, as in you could reduce their number by perhaps 2/3 and you would get the same results (probably better).
Where do you work? I've rarely experienced this. Current and last company, both fast moving adtech firms, we are always desperate for good managers. BUT the key is only to have managers with, well, management skills. That does not mean promoting the best engineers to management, a common problem. In fact it is often specifically not that. They get promoted in the tech track.
The book "Managing Humans" is worth a read if you're so cynical about managers. Though the actual problem is corporate culture in my experience.