It's hidden, I suspect, so that changes to the underlying math involving that information can be made without players calling the developers names. If it's not 'official' it can be changed as needed.

That being said, there are a few sites on the Internet (and on Discord) where that underlying math is better understood due to players reporting what happens by observing what happens when X is cast or Y action is taken. It's called theorycrafting and/or optimization.

Have fun investigating!