Here's a fine think-piece by Susan Cain that praises some introversion as indispensable for creativity. To some great extent, Socrates and Jesus were solitary men. And the wisdom they shared with us couldn't have been captured in group reports or multi-authored articles.
Not only that, we live in a society that discourages, in so many ways, thinking for ourselves. We defer so readily to public opinion, fashion, and what the experts say and the studies show. Most studies that show stuff have a lot more than one author. Most books that change our lives have only one, and we don't live in a time when many are being written.
Just about every good play or novel or painting, of course, has its source in the vision of a single artist.
We also see, of course, that in the disciplines that require deep thought and personal interpretation (such as philosophy—especially political philosophy—and history), articles almost only have one author. Technical and scientific reports usually have more authors than they do pages.
If we want learning to be personal, personal thought has to be encouraged and rewarded. And persons, of course, have to be held personally responsible for both what they've learned and the ways in which they have expressed their thoughts.
In a class dealing with "real books" (such as ones written by Plato or Kant or Jane Austen or Pascal or Simone Weil), I find that the best students get less than ten percent of what's really going on, and "what's gotten" differs dramatically from student to student. If they had to produce a multi-authored paper, the result would be flattened out to what they can explain to each other. It goes without saying the good students would be particularly shy about expressing their most unconventional thoughts to each other, especially ones that have to do with God, love, death, and such to the other group members. They would also be shy about being too enthusiastic or "erotic" about what they've read to others who just didn't work as hard or care as much as they did. (All this is why I can't stand "peer review" as even a stage in evaluating student papers.)
It also goes without saying that the natural result is for good students to have quite different views on the truth and significance of what they've read—in part, due to what else they've read and their personal experiences. How could they possibly write a conclusion based on some consensus that's more than a bunch of feel-good banalities?
Good students do, of course, learn from each other through conversation. Part of a great class is something like a Socratic dialogue—keeping in mind that the participant closest to Socrates (me) dominates the discussion in various ways. The community of learners doesn't mean that all the learners are equal in the ways relevant to actual learning.
In the end: The student paper should be a rather solitary, introverted effort, although not one so introverted that the author is not excited about the possibility that the truth can be shared in common. "Shared in common" in the Socratic sense is a long distance from groupthink or what's usually meant by collaborative learning.
Another problem with "group projects" as a learning tool is that our society already rewards being witty and fashionable and pleasing to others far too much. It also already rewards too much shirkers whose main talent is taking credit for the real work of others. Let sucking up be saved for the actual world of business. It's not a skill that should be rewarded by college credit.
Here's another problem: Collaborative learning is also often an excuse for professorial laziness. Why read twenty papers when you can read five (written by groups of four)? The group dynamic also means that the papers will only be so good or so bad, and that means that the professor won't be taxed by a product that is too "outside the box" of what's expected.
If you ever sign up for a class that's a mixture of PowerPoint presentations based on some textbook followed up by group projects and presentations, immediately drop it and ask for your money back.
The philosopher Rousseau was against taking the idea of dispersing wisdom to everyone characteristic of the Enlightenment too seriously because the real goal of that approach is the production of a vain and pseudo-sophisticated herd of seemingly meritocratic techno-elitists. The philosopher—or the genuinely Enlightened person—is always a law unto himself. He's almost always not characterized by the ambiguous virtue of working well with others.