Working and learning in groups is more fun, and you get more done. Complex problems are often more easily solved by a team, than an individual, especially when the team is made up of people with diverse points of view. People maintain the expertise they bring to teams, by associating with others who share their expertise. Work is more fun and interesting when you have people to swap notes, and toss ideas around with.
It's hard to beat collaborating in the same place at the same time, especially when you want to hear from everyone in the group. It's often difficult, however, to meet face-to-face. People may have to travel, but even if they don't, it's often hard to find a time when everyone is available. And face-to-face, each person can only participate in one conversation at a time. The larger the group, the worse these problems get.
The obvious benefit of collaborating online is that you can participate from wherever you like. There is no travelling required. Collaborating online, however, also means that people don't have to participate at the same time.
Online collaboration does have disadvantages compared with face-to-face. There is no voice tone or body language, making it much less immediate and dynamic. These disadvantages cannot be overcome, but they can be mitigated by effective participation.
Taking time to communicate your ideas clearly makes them easier to find. Others are more likely to pay attention to you, and more likely to respond thoughtfully.