There is no advantage.
Most people in this forum are from a technical background, so they automatically look for technical solutions.
You don't write a book how you write code. When writing code, you dig in, change a line here, add a function there. This can break the whole system, which is why you have version control and testing and continuous integration.
Books, and especially fiction, isn't written like that. Perhaps if you are writing a technical book, it maybe useful, but I'm not sure how. You write your first draft, where you type in everything you have. And then you start a new draft, where you fix any issues you want. And so on, for as many drafts as you want.
With code, you can make hundreds of changes in a week, which become impossible to track, which is why you need version control. Do you really write hundreds of drafts? If not, using version control is an overkill.
I don't agree with Monica's answer. I have never felt the need to "branch" my book. If I want to try something new, I just create a new chapter (which in Scrivener, is as simple as creating a new text page). If I don't like it, I remove it in the next draft. Using Git to "branch" out everytime you have a new idea is an overkill, and not the way most authors work.
More importantly, it looks like forcing the tools of one domain to another, without understanding why those tools are used in the original domain.
Summary: Use version control if you like it, but it is not required; I'll go one step ahead and say its a distraction, another toy that stops you from working.