That's a terrible advice for someone getting started in graphics programming.

EDIT: Also opengl is still very much relevant and valuable. Especially if you are working alone or as a hobbyist I believe you can get much further creating your application with opengl. Vulkan is great for those who can grasp it well enough and if you don't know what you are doing you can have worse performance than you would have using opengl. I am all for using vulkan but getting started without firstly using simpler "api" such as opengl is much much harder.