In 2026: Yes yes, please please learn this if you're beginning computer graphics. This is basically the One and Only Holy Bible of graphics programming, and dealing with a slightly outdated and weird API doesn't make it worse even a teeny bit. You will never get the same quality of fundamental education material from any of the other tutorials (especially Vulkan ones, since most of them assume you already know the basics and delve straight into writing thousands of lines of code that doesn't even perform better than OpenGL). You need to first learn the really basic things like homogeneous coordinates, matrix transforms, vertex and fragment shaders, various shading models like Phong and PBR, multi-pass rendering, etc, before actually diving into lower-level details where you want to optimize things.

Vulkan and DX12 are currently flawed APIs that are unnecessarily complex and doesn't even match the performance characteristics of current-gen hardware (see the titular post: https://www.sebastianaaltonen.com/blog/no-graphics-api) - if you want to really learn the low-level details you should start diving into something like CUDA or get into graphics driver development (start by reading Mesa open source driver code - which you will then learn why Vulkan is flawed)