Often, the time spent on communicating could get job done.
It's also difficult to find collaborators who are on the same page. Often you need to spend time educating team members.
Collaboration and communication are unavoidable for large projects though. I therefore have to stay minimal for side projects.
But what if people contact you (instead of you reaching out to anyone) to work with you because they think your project is cool (or some other reason), would you then prefer working with them (assuming you think they are a good developer)?