That is the test of good brisket - gotta be sauce less (except burnt ends). If the pitmaster is serving it sauced he’s hiding dried meat. But people like condiments so I serve sauce on the side.
The crutch started as foil, but as you note it actually steams or besides the meat. It shortens the cook a lot. Wrapping in butcher paper is like halfway between foil and naked in terms of cooking speed enhancement. It also helps cook the brisket faster but not as fast as foil. The benefit is that it breathes unlike foil so you don’t steam your brisket and lose the bark.
Maybe it should be called the Texas cane?