You can point to the pages of your book all you want to. You can imagine stuff in your head all you want to.
The fact is that nothing happens, in the fiction of role-playing, unless someone says it and it's heard by others. Even if the book says, "On a critical hit, you do double damage," your character won't actually do double damage on a critical hit unless someone recognizes it and says it.
Role-playing is made of talking like apple pie is made of apples and crust and scary amounts of butter. Whatever mechanics you use, you are agreeing to use them among the group, usually as a creative inspiration or constraint, specifically as a way to affect what is going to be said.
"System (including but not limited to 'the rules') is defined as the means by which the group agrees to imagined events during play." The author of the principle is Vincent Baker, see Vincent's standard rant: power, credibility, and assent and Player power abuse].