Even if everyone in your group is trying to put the effort in and not a flake, arranging meetings in our modern world is a pain in the fucking ass, especially if you all have day jobs.
But if on top of that you do have one or several people in the group who are flaky, or lazy, or just suck at doing research you're put in this shitty situation where you either have to nag their ass to work, or just do their work for them. Which then leads to you being tempted to act like a cop and NARC on them to the prof in order to protect your own grade.
The only time I've enjoyed group projects is when the prof set aside in class time to work on it, otherwise it's a shit show, I'll take writing a paper myself over this shit any day.
I had to do them for college lab reports and it usually fell to me, there's only so much one person could do then everyone sobbed about their B paper and the next time actually did their jobs. Where/when I went to school if you told the professor your labmates were slacking they'd just be like
"figure it out you're all adults."