Writing it all as code would exclude nonprogrammers just as much as this excludes people not familiar with basic mathematical notation.

At least everybody should share some common mathematical instruction from school. The same certainly cannot be said of programming.

As somebody who can read both code and math, though, I'd greatly, greatly prefer to see math in math notation, not code. Code would be so much more verbose that it would take easily twice as long to digest the information. You'd also completely lose all the incredibly powerful visual reasoning that comes along with modern mathematical notation.

This is abstracted and very understandable. The picture is the definition of a function, which in turn invokes the definition of other functions. The P's are abstractions for conditional probability, the sums are loops etc. If this were code, it would be no more than a few lines and very understandable. Unlike code however, for all this there is very thorough documentation for mathematics in millions of pages by thousands of people in many different languages at all levels. The documentation is textbooks, and they're pretty good.

But those functions might still be cryptic. And the rabbit hole may go deeper than the amount of text one can be reasonably allocated to a discussion.

Consider how much work Bourbaki had to write before he/they got to real analysis.