It is all in the rectangle. By this I mean that with human hearing, we have limitations. A certain spectrum and a certain decibel range. If you map this out you will create a rectangular graph. Knowing these limitations, we must make choices. The box can only be so full. If you want to put something in a box that is already full, you must take something out. If you put something fragile in the box and then put something heavy on top of it you will break your fragile item. For fragile things you need space and protection. If you load the box with heavy items, nothing will break, but no one will want to pick it up likely. These stupid metaphors can be helpful when it comes down to important decisions in mixing and editing.
Carving out frequencies in a mix can be paramount when it is a dense production. Getting rid of frequencies of a track that are not needed for the particular sound, so something else that is needed will have the room for it. If you are an engineer or an artist who is layering on track after track because in this digital age, we can. Realizing that in the end, it must be heard in the limitations of human hearing and human discernment. We are limited. Thankfully so, I feel, because we have to make choices, and in these choices come clarity. Leaving what counts...what is integral for the piece remain, while pushing the superfluous aside with their faders down, on mute, or just delete.
I prefer delete. Make it final. Vacillation becomes impossible and to embrace what is left and making it the best it can be while still remaining vital, emotional, and real.