Currently Discourse is already very flexible in making things work. I would definitely structure courses (or anything alike) using the new doc-categories plugin. Example structure in production here on meta docs.
There are for sure things that can be done to make Discourse more inviting to this category.
Versus Skool, I’m 100% sure that you have more flexibility in designing the overall structure with on Discourse, Skool looks very simply structured. They only have categories, in Discourse you can combine both categories and tags, but also sub-categories. Discourse on the other hand, can be as simple in structure if you want it too.
Skool seems to be easy for subscriptions, also possible with Discourse Subscriptions but I agree, the Discourse way is not as easy as Skool. You’d have to setup I believe Stripe or a similar payment provider, which makes sense, Skool probably takes a cut on all subs. It’s a whole different structure and more like a freemium route, think of CDCK offering free hosting and monetizing by commission over transactions happening on your community.