I think you’re right about how vocals cut through being the determining factor. And treating the modelers output as if it’s a vocalist and EQing that way results in a horrible-sounding guitar tone.
A FOH engineer thought he was helping me one evening by, unknown-to-me, routing my FOH feed to some side fill monitors and re-EQing it. It was bright and piercing without any lows, and I thought my rig had fried something and tried adjusting the feed to my EV with no improvement. Finally I gave up trying and limped through the night. At tear down he asked how I liked having my feed through the side fills… um… “side fills? Huh?” and he told me what he’d done. I nicely told him to never, ever, do that again, that my EV is plenty loud for me, and the next morning set my rig up in the garage and turned it up to confirm that it was all working correctly. My girlfriend told me later, after tearing it down and putting it all away and returning to the house, that it sounded really good out there. Heh. 50 feet away through multiple adobe walls in a separate building she could still hear it.