It's quite possible that this is a function of having so little open content out there right now. I can imagine a future where the background your wife needed would be easy to get from the platform itself, so that the profs' demanding teaching could serve audiences both with and without that background. Right now many of these courses must feel like skyhooks but once they're embedded in a web of knowledge (an earlier commenter called these 'nodes') they'll be more accessible i think.
There's still a huge problem of collecting and sequencing these nodes and I think many students will need direct contact with instructors of some sort to do this.