Yeah I think almost anyone will agree that these matrix formulations are more confusing than helpful. The subject itself isn't really that complicated, but the jargon and notation makes it a lot less approachable than it is. Unwrapping the operations with explicit summation makes it a heck of a lot clearer what is happening.
There are places where matrix expressions are informative and helpful, but at least in the context of teaching machine learning, this isn't one of them.
There are places where matrix expressions are informative and helpful, but at least in the context of teaching machine learning, this isn't one of them.