Some more interesting information from Qt’s blog:
The Problem
What about modern OpenGL, though?
That is where the problems started appearing: around Qt 5.0 those who were in need of a core profile context due to doing custom OpenGL rendering that needed this ended up running into roadblocks quite often. Components like Qt Quick were initially unable to function with such contexts due to relying on deprecated/removed functionality (for example, client-side pointers), lacking a vertex array object, and supplying GLSL shaders of a version the support for which is not mandated in such contexts.
In some cases opting for a compatibility profile was a viable workaround. However, Mac OS X / macOS famously lacks support for this: there the choice has been either OpenGL 2.1 or a 3.2+ core profile context. Attempts to work this around by for instance rendering into textures in one context and then using the texture in another context via resource sharing were often futile too, since some platforms tend to reject resource sharing between contexts of different version/profile.