Good point. In this case we had a misapplied "dual-track agile" structure, which in theory means the whole organization is "doing agile", but since the feedback loop is super long, it's indeed just waterfall-with-extra-steps.

This is not the first time I see this happening. Product Managers love it. IMO it is classic micromanagement. Product Managers want more control of the process than is afforded by a "self managing agile team", so the only chance of control is achieved by isolating team communication and having "small" deliverables that they have full control over. IMO that's alright, but it's waterfall. You can't expect the advantages of an agile process to apply to this.