But they're the project leader. They're calling the shots so you use what they specify.
Most projects let you pick your editor, filesystem, distribution, etc. It would be nice to add version control to that list. That doesn't seem like it would be all that hard to do. There are already tools to migrate a repository between different version control systems and they mostly use similar concepts.
Computers are unreliable, but humans are even more unreliable. Any system which depends on human reliability is unreliable. -- Gilb