They tried that, it turned into this metagame with reprisals where others would work together and gang up on you so it would end up being many against one. Basically step one was to find the sucker, step two is make it stick. If you had a rep for good grades then you were de facto the sucker. You could tank the group and hope to fair better in a reshuffle but it was a lemon market and the replacements would be just as bad and now everyone knows you have given your previous team members poor scores. People quickly learned to never do that. So part of the optimization was to present lecturers with what they want to see with only minor deviations between individual rankings, effectively a voting ring. Presenting a false projection of reality in order to metagame politics was accidentally good training for real world work - but it really sucks having to do the work of 4 people.

I’m sure if the lecturers cared they could have managed it properly but they didn’t I don’t know of any who did.