In real life, however, you are judged by a human mind, not by a computer. A point system won't reward that pikeman that warded off multiple cav from hitting his team's flank, or the shielder that spent the whole round deterring ranged enemies from shooting his team, or the cav that bumped a dangerous enemy at a key time. It will only reward the guy that ran in and hit a bunch of people with his sword.
Not to say that guy that actually did the damage was worth less than the others, but just that the score system only rewards him, not the others who were equally important for the team.
It is very difficult to determine exactly how well someone did individually with an algorithm, as such rewarding the team (and thereby on average individual key players) is the only way to reward those key players that didn't actually deal much damage.