Just because there is one project apparently using this in a way that indicates someone could perceive something as a weakness... It doesn't mean it's a real weakness (nor that it's serious).

You can just not move branches. But once you can do it, you will like it. And you are going to use

   git branch --contains COMMIT

which will tell you ALL the branches a commit is part of.

Git's model is clean and simple, and makes a whole lot of sense. IMHO.