No one is denying the need for PMs. OP is pointing out that PMs have too much decision making power, with too little accountability in most organizations.
Your argument is akin to, "PMs can't code, so alas we need engineers, and that's why shitty engineering exists, and there is no way to make it better"! Nope! We need product practices, akin to engineering practices, with 360° feedback and analysis, and the product management should be held accountable for their decisions!
Right. And I'm saying that is because engineers don't want the responsibility that they often request because the entire point of PM's existence is offloading that responsibility. They seem more than happy to complain about it though
This is still missing the point. The way to improve PM accountability isn't engineers fixing them. It's the organization's and leadership responsibility to ensure PMs are held accountable.
Engineers would be far happier if they don't have to do good engineering and can do away with shitty software without accountability. But there are checks and balances to improve engineering quality, and those aren't created by PMs. It's the engineering org that champions good engineering practices and accountability and post mortems. Same should be done in PM organizations.
Your argument is akin to, "PMs can't code, so alas we need engineers, and that's why shitty engineering exists, and there is no way to make it better"! Nope! We need product practices, akin to engineering practices, with 360° feedback and analysis, and the product management should be held accountable for their decisions!