> Part of the problem is that many of the concepts OpenGL teaches you have no bearing on how modern hardware actually works, so you end up having to unlearn bad habits which OpenGLs messy abstractions enable. OpenGL won't teach you to think in terms of PSOs, for example.

While this is true, for somebody who is starting from scratch there is a lot to learn before getting to the level at which thinking in terms of PSO is important, and it can be easier to get there via OpenGL, which btw still teaches you a decent chunk of GPU-friendly patterns (assuming of course we are talking about "modern" OpenGL and not display lists and such...). Also, with a good command of OpenGL, one can start trying to understand and re-implement rendering techniques spanning from deferred/forward+/clustered lighting, the various shadowing techniques and even HW raytracing eg. via the GLSL_NV_ray_tracingextension, which is - in my opinion - the more important side of learning GPU-accelerated rendering.