Any new concept or tool dependency, e.g. 3D editor or shader, is a pain point here since it increases project compexity superlinearly.
Also, many "game engines" which aim to speed up development impose a lot of constraints on client code. For example, they're not compatible with non-GL windows from same process or with external event loop. I made a mistake trying to use a few of those and impedance mismatch was really painful. Had to divest to plain OpenGL.
Vulkan isn't a higher level API though, which might be why you and the other guy are kind of talking past each other.
Realtime rendering is independent from game engine implementations and especially from content creation pipelines. If you are looking at resources that explain how to use game engines then you're looking in the wrong place. What you want is resources that teach how to write rendering code.