Here's an example of what I'm talking about. When mixing guitar/bass/drums, I'll often high-pass guitars around 200hz - basically, throwing out any signal below

Here's an example of what I'm talking about. When mixing guitar/bass/drums, I'll often high-pass guitars around 200hz - basically, throwing out any signal below that with an equalizer. And if you listen to the guitar by itself, it sounds like it's been gutted. But in the context of a mix, the change to the guitar is inaudible - but the drums and bass sound better! The heart of the guitar's sound is in the midrange, not the bass range. You can lose the bass range and as long as other instruments are there, your ears fill in the missing information for you. Meanwhile, the heart of the kick drum and bass guitar are in that lower range, so getting other instruments out of their way makes them easier to hear.