You mean Little Fat Boy 2 ? I can guaranty you that the jam version was less cooler than the one you played. Cause I also continue to work on the games after jams ends when they deserve it. 72H is really super short for complex games like that.
I don't know, I never collaborated with anybody, and I really tried (to try at least). But I just can't, too solitary I guess, and having total control of every aspects of a game is mandatory for me. I love too much making art, then 5 minutes later coding, then making music, then adding my own bugs, etc... And that's precisely why I loves making games, they just calm my ADHD.
There are a lot of games here (I won't give any names), which were made by 1, 2, 3 or even more people, even talented ones, but the result looks like a complete waste of talent. Due to all the artistic, design or thinking divergence the devs had, especially when you make a team on the fly for a jam.