Yeah, it's true that many of these "bestselling courses" are build for newcomers. They are made in a way to not scare off the person, and then they promise you that in 24 hours you will learn c++ or < insert any complex enough topic >. But the people who sign up usually don't know or have any idea about the market of that skill. And what you need to know and be able to do, to be competitive. And how to progress up from there.

These courses are dragging sometimes for very long, and then they don't connect ideas/concepts from before with current material.

But that's not to say there are no hidden gems in industry. There are many small/just starting teachers and they are willing to put their best effort first and forward to establish on market. We need more people like these.