Really? That's news to me. And I study programming in school. Usually people use version control software and hopefully a decent branching model. And if you have designed your software beforehand, you wouldn't be "getting at each others' throats".
Well, you study programming at school while I've finished University and already have already worked as a programmer. So there you go, no sense in showing how big your dick is.
Yes, using a version control software such as TortoisGit helps with this stuff, but there are problems with branching when there are a lot of coders one way or another, there are still a lot of problems when brunches can't automaticly merge and you have to tickle everything with your own hands, which requires additional communication and time waisting. Surely everything depends on a set of diffirent factors such as the project itself, how difficult it is, how many people work on it at the same time, how expirienced they are with coding and version controll, how much they cooperate e.t.c. But one way or another there are problems, and depending on these factors developing can go as smooth as a river or as sharp as rocks, but general idea still stands - the less coders project has, the less problems project will expirience, because different people tend to work different ways (code different ways), the less ways - the less problems, its simple as that.
In big studios such thing can be taken down to a minimum by additional studying that management can actually provide their staff, but when talking about patreon and indie projects - theres none of it. People have to advance on their own and that can bring up a lot of unforseen difficulties.
So yes, the less coders - the cleaner and smoother the project can go.