Isn't this much closer to RefCell than the borrow checker?

Dispatch ambiguity can really bite you, particularly if you start extending methods from other packages. An issue I often run into at the same time as method ambiguity is a stack overflow from self-calling constructors. If you try to define an outer constructor with default arguments, it's really easy to end up just calling that constructor from itself.

The metaprogramming trick for defining a set of methods at once is useful, but I wish there were a more compiler-level solution to sorting out ambiguities or determining what's more "specialized".

These don't really color my view on multiple dispatch, however. I find it to be a really useful tool and I don't run into dispatch issues very frequently. If you're meticulous about your typing it's usually easy to avoid these pitfalls, but sometimes they still crop up.

The archive is a few years out of date: https://legiblenews.com/archive/

While I was in grad school, I had to teach some math-heavy engineering courses. This lesson came through very clearly there, and learning it early made my teaching much more effective.

You can't tell students anything, you have to show them, and you have to know where to start when you show them. Sometimes this meant starting back in the prerequisites to the course (a brief refresher on ODEs) and sometimes it meant arguing by anology before returning to the topic at hand.