Vulkan is almost 1:1 equivalent to "modern" OpenGL except the need for a more advanced allocator. You had to write the exact same thing in OpenGL if you wanted decent performance, except through an entire translation layer.

I don't think anyone who actually worked on a serious engine thinks it's somehow harder to use. Sure, there's more boilerplate and it might get pretty difficult to port something to it, but that's something else entirely.