OpenGL is limited to 4.1 on Apple platforms if I am not mistaken, and will not get updated ever. So you will run into missing features eventually on some platforms, e.g. SSBOs are really nice but you can't them use on Apple devices.

For me, a much stronger argument against OpenGL is that is requires a global state. This often leads to bad design, is miserable to multi-thread, and is rather tedious to port to Vulkan. I have spent several years fighting with multi-threading applications doing all sort of things in OpenGL and it is not great. Yes, Vulkan is extremely painful to set-up and you have to think about a million things you might not really care about directly, but honestly, I would also recommend against starting anything serious in OpenGL. To get your hands wet maybe, as with a couple lines you can get something running..