Alone, the MCAT, your GPA, your ECs, they don't really show much about you.
I'm sure there are tons of people with good MCAT scores but bad GPAs, good ECs but can't take a test to save their life.
All together...the physician you want is someone that can perform under pressure, but still has a human side.
Yes, to get through studying for the MCAT is tough, but to show your commitment to others through keeping with ECs, all the while performing well in school and excelling on standardized tests...well, together, maybe those people might be the ones you want.
If you throw out one piece of the puzzle, the pressure to excel in the others will go up. If we only look at ECs, you're going to be seeing a lot more sociopaths in medicine.
But it is more difficult, IMO, for someone to game GPA, MCAT, and ECs. The point is you're figuring out who wants it the most, who has the determination and the skills to make it. Straight up ECs = sociopath ass kissing fest, Straight up academics = Dr. Asperger.
The force requires balance.