A thought for this evening - does the lesson and course structure part make it more difficult.
The other way is to just post posts and use quizzes.
There isn't a way to submit assignments like that, though that could be done by email or contact form. The Namaste LMS assignment system is a bit tricky to use at the moment - lots of clicking through.
Also, with the free level of Namaste LMS the order of lessons comes from the order they are written, not their position in the courses. So while I'm jumping around from one course to another as I write, the next/prev lesson links are a bit random.
Lessons could be grouped together by tags instead. Or categories - hmmm... probably good to work that out before I get too far.
WordPress is very flexible and stable, so it should still be a great platform like that.
All the lesson material would be open - which is great from a search engine optimisation point of view - but the quizzes could be restricted to logged in users in order to keep track of who has done what.
I'll sleep on it.