[itronitron]

The goal with the matrix management is to distribute the risk. If your people manager puts you on a PIP then at least your project managers will have some ability to push back on that.

But there is no good reason for the People manager to care anything about what projects have people working on them. If they start to care about which projects are successful instead of all projects are successful then they're not a good fit for the job. And yes I have experienced that, as well as it's opposite.

[pas]

and this leads to 4 engineers and 6 managers sitting in a meeting, and nobody actually being responsible for anything.

no, of course, there's a lot of value in providing escalation/descalation/rehoming processes, and dedicated ways for org-wide feedback on people's and projects' impact, but people are not just three orthonormal roles on top of each other in a trenchcoat, if there's not clear hierarchy then - as others pointed out - the informal chaos takes over (because it's the human default)