People who dont use most of the software are beginners who dont realize that the rest of the software contains tools that will make their life far easier. No user ever sticks to a set of features.
rendering is very useful to render stuff you would not want unreal to render because of speed or unreal simply cant render. You can import those renders back to unreal as baked textures, backgrounds , matte paintings, video walls etc to create the illusion that the engine is far more sophisticated than it actually is.
So yeah leaving everything to the game engine is not a good idea.
If you switch 3d software because you found a bug, be ready to not last long with Maya. Its better to post your problem in the forums, and if it is a bug, open a bug report. I never had problems with blender and fonts, but I have other problems like CUDA being super unstable, which is unrelated to Blender but still does not let me to use GPU rendering.