It's always more of a problem with "accessible" software like Blender. Next to no barriers to entry results in too many content creators and too little knowledge. Couple that with the fact that Blender hasn't yet become an industry standard, and there just isn't the same kind of tuition available.

Meanwhile convoluted and expensive industry staples like Houdini have almost consistently good content. I'd wager for a lot of the more theoretical topics, which are largely software agnostic, you'd be better off picking up the basics anywhere and then moving onto something more reputable for the theory and advanced topics even if the course uses another software package.