In fact, when you look at the progression from OpenGL 1.1 to 3.0 Core to Vulkan (and the parallel evolution of Direct3D), you'll see that with every step along

In fact, when you look at the progression from OpenGL 1.1 to 3.0 Core to Vulkan (and the parallel evolution of Direct3D), you'll see that with every step along the way, the APIs became more and more flexible by providing less and less convenience. Just look at the code it takes to render one triangle using each one of these APIs. The difference is that by the time you manage to render a triangle using Vulkan, you're also mostly set up to do very advanced rendering tricks that would be plain impossible with OpenGL 1.1 and would require some contortions to get working on OpenGL 3.0.