`git rebase` is fairly useful when differences are small. Rebase changes the history of your own commits. When that history is long (you've got a lot of commits that are not in the other branch), you'll end up resolving the same conflicts over and over and over again, and in that case, a simple merge is much less painful.

The only real advantage of rebasing is that it keeps your history linear. A history with merges is harder to navigate. But at some point, merges become unavoidable, and the larger the differences are, the more important it becomes to use merge instead of rebase.

And as any time traveler knows, changing history comes with risks.