When I was doing sound reinforcement and doing live and studio recording, I would do two separate recordings. One being flat with no pre fader FX or EQing and another with post recording, with deferent FX and eq settings to make it sound the way I wanted.
With the pre fader recordings I had a snapshot of the actual sound before any coloration from any equipment.
In post recording I have it tweaked to sound good.
With the pre fader recordings I can more accurately control the out come because nothing has been given or taken away from the sound.
With post recordings the sound has been altered somewhat and I can’t always change something that has already been done.
You are correct, no two of anything is exactly the same. Or sounds the same to everyone.
If flat was the best way to hear it and all HIFI equipment were exactly the same and every room was the same then there would no need for an eq of any kind.
But in the real world we all have an idea of what sounds good to us and every room is deferent.
Dennis