As I mentioned in a sibling comment, the toxic (and incompetent) manager problem is fundamentally a leadership problem. The single biggest responsibility of the founders is the culture of the organization -- everything stems from that, one way or another.

Leadership, from the top down, is absolutely responsible for the mentoring, training, and environment created by the management. None of the systemic problems with & induced by management is new. It comes down to: does leadership actually care enough to do anything about it? Companies institute all sorts of formal stuff like internal surveys and NPS scoring and so forth but it always comes down to trust & communication and then follow through. And the follow through is the clearest way to create trust. All of the things that even well intentioned leaders spout, if not followed through, quickly erodes and ultimately destroys trust. So, just like with kids, don't make promises you won't keep.