Because it’s ridiculous to expect someone who is paying for an education to have their grade partially dependent on anyone but the person who is paying for that education. Which would be themselves.
The time for this kind of thing is grade school, when you don’t know any better, and think sharing your toys is the worst thing that could possibly happen to you. You learn how to behave in a group, how to take responsibility, how to work together, at a time when you’re malleable enough for it to sink in and stick. Elementary school, middle school, sure, even high school I can see teaching like this. But grown-ass adults who can vote and get into college should have already had these lessons. Why should one of the steps to my degree and my future depend on someone might not give a crap? I’m not here for the life lessons or to help anyone who somehow missed out on basic human interaction over the previous eighteen years, I’m here for my damn BA. Spare me Remedial Cooperation and let me earn my grade.
I wonder if it’s a way for a professor to only have to grade four or five projects instead of twenty. I hope that’s the case. At least somebody would be getting something out of it.