And a monad is just a monoid in the category of endofunctors.
This stuff is not obvious to everyone. The arbitrary numbers are called an example.
The point of the article is to say, when you experience a plateau and you begin to speculate why, it’s mathematically expectable.
1. Be clear that they're examples and not some fundamental, mathematical truth.
2. Use multiple examples with different numbers to show how things could look different, even if only slightly.
The author does neither of these. #1 is violated in the title. It's not clear at all that the author is using these numbers as merely examples.
It can hardly be controversial to call this math.
But ok, it’s not “the mathematical reason” but rather “a mathematical explanation” - the math is a property of his explanation, and the reason is growth, churn and employee psychology; while well-explained mathematically, they aren’t math.
Somehow this seems to be besides the point, being: here is a common reason for plateau’ing.
After a lengthy manipulation of the integral, he said "and then you can just plug this into a calculator and get an answer, but that's not really interesting so I'll stop here".