> There's no definites in software development but if a formula is repeated 10 times you probably have a good name for it and at that point it probably should be in a function.

I don't think your take makes sense. The example in the blogpost states multiple methods have 10 lines of math, but even the author mentions they were similar, not the same. The use of the weasel word "similar" already tells you that it wasn't the math that was shaved off. In fact, the supposedly brilliant refactoring that the blogger did was change the whole interface without any good reason, and with bad object-oriented inheritance chains and mixins to boot. What a mess.

Still, the blogger tries to claim this is clean?

There's a good reason why the blogger was pulled into a meeting and gently forced to revert that mess back to its old state, and why the blogger decided to depict a hero journey in a blog post where any sort of counterpoint is left out.