I can show you file after file at -12dBRMS that are *apparently louder* than file after file at -10dBRMS. The number doesn't mean all that much.
And generally great sounding mixes done by teams of proffesionals at every single stage in the game working with core sounds that are tweaked for hours - days before the "RECORD" button is ever pressed for the first time - It's not a big surprise when that kind of quality sounds better @ louder.
I'm not sure what your experience / gear / capabilities are - But the vast, vast majority of mixes will *never* have the "loudness potential" as those that can handle that type of abuse.
Personally, I wish *none* of them would... But that's for another thread.