Earlier quoted context omitted.
I'm pretty sure he means "it is an easy equation to memorise, but it's not trivial". People can remember the formula, but have no idea how it actually works.
Memorizing equations is "religion" not "math". "Understanding" is "math".
The amount of crap I got for using the "wrong way" to calculate something in math class, was probably one of the major reason I never really got into it.
I remember math classes in the beginning actually being fun, I loved figuring out more convenient/to me more logical ways to calculate something, only to be constantly shut down by the teachers for using them, as he/she demanded I use the solution given by the book.
I do understand the value of getting to the same solution in different ways, I even did back then, but teachers didn't frame it like that; their insistence on the book solution just felt like an accusation against me of not understanding, telling me my way of calculating is wrong (even tho they usually proof calculated right) when to me it looked like it was them not understanding, by insisting on that one formalized, and often awkward, solution, and only that.
So as a somewhat rebellious character, it didn't take long for me to start actually despising math classes.
If I could go back I'd probably try to do it differently, I'm in my mid-30's now and consider myself "math illiterate". Sure I can do most basic stuff and even the occasional Pythagorean theorem (which fascinates me to this day, take two knowns to figure out the third unknown!), but I still feel like I missed out on something I could probably really have enjoyed.