Learning by failure is how you learn in school it's why they teach you the same thing over and over again and give you a chance to fail at it in homework. Also, and again, learning how to DM isn't like learning how to do math or how to write a constructive paragraph. Learning how to DM is like learning how to play football, you're going to end up knocked on your butt a few times before you get really good at it, and even when you are really good at it you are still going to get knocked on your butt.
The reason it is unimportant to tell them x is x because of y is because none of that actually matters once we are in the table. All that matters at that point is numbers 1 2 and 3 from above. If the RAW is holding up one of those three points, will eff it make something up, and if that new ruling stops working try something else out. Make sure your players are okay with how things are working and just keep going. Eventually you will figure out what works for you and your table.
I've seen a million different house rules, some I'm down for and some I'd never play with, but someone does play with those house rules and they ostensibly either enjoy those house rules greatly or can tolerate it enough to keep playing with it in place (otherwise no one would be paying with that house rule). At that point out comes down to properly communicating your feelings and the guides aren't big enough to cover how to do that.