It's interesting that you talk that there's a lot of good management, followed by a list of things I'd call bad management: Forget about good vs bad code, of course that's unimportant. But insufficient maintenance that causes lower velocity on the next set of changes matters. Good engineering will tell you when the issue isn't just about code that is ugly, but code that slows changes down so much you'd be better off improving it.

If you set incentives that say that being sloppy and leaving landmines for the next group of people is the way to get promoted, guess what? the management is bad. Often because they are also looking at their own self interest, and expect to leave the consequences to whoever comes after them. This isn't new to big tech: You'll find this all described in books about corporate dysfunction written in the 90s.

It's all traditional principal agent problems, which just get worse and worse as you add layers of management, as the principal has agents upon agents underneath, all using the misaligned incentives. One either wants t avoid getting fired while doing the minimum, or sacrifice the health of what is around them for a good enough promotion packet/review. And since there's no reasonable way for individual objectives to align well with long term objectives, people leave landmines. When there's enough landmines everywhere, you are always better off in greenfield development. And at that point, doing any maintenance, or being stuck in a project that isn't getting fed a bunch of capital to grow it is career suicide. All about bad incentives, set by bad management.