I agree with you, but I think it does depend on the goal of the tutorial/class/whatever.

I teach an introductory university 3-D graphics programming class, and I use legacy fixed-function OpenGL at the beginning, and then legacy GL + GLSL for lighting & textures.

But then my goal is not to teach people how to use some particular API. I want to introduce principles of lowish-level graphics programming. I need to use some API, of course, but I can choose that with a view toward how helpful it is in teaching concepts (and also system independence).

OTOH, if I were running some kind of training seminar for people who wanted to go out and write the world's greatest game as soon as they were done, then my approach would obviously be a pretty poor one.