I agree with everything above. Mastering used to be a different thing than what it has turned into today.
I've had the task of actually mastering a couple metal albums after they were mixed in a studio. I would do two versions. One with some light hard limiting on parts to make a more punchy sound but keep a full dynamic range. Making each track on the album sound even to each other.
Then I did another version where I smashed everything into a hard limiter. The mix had an RMS of about -.1.
Guess which one they picked?
I could talk hours about this. The whole deal with engineers thinking if they smashed the dynamics it would make radio station processors leave the sound alone. Or about tape saturation in analog recordings. etc etc