I guess many tutorials are not made for absolute beginners and they have assumed you have learnt the basics before jumping into their topic. For example, if you never learn programming and set up an ide before, it has no way you can learn OpenGL as your first tutorial, and all the syntax and commands will look alienated.
And you can't write every document with an assumption that the reader knows nothing. Each document would end up the size of a phone book if you explained every single piece of technology used and provided tutorials for them.
Knowing where to jump in your stack is a tricky question, though.
OpenGL is not so bad because the API is quite stable. WebGL in particular is great because there's literally zero setup you need to do for executing it.
Integrating with Linux/Windows display surfaces is disgusting however. KMSDRM is way, way better than the nightmare that is X11 and Wayland.