Different git branches don't allow the features to be vetted by users. At least not by many users. It's going to be much harder to get users to use different builds of Chrome than it is to have different (or even the same) people using Chrome and Firefox.
Also, what management team is going to ask their developers to work on two conflicting features in parallel? It's a people matter as much as it is a technical one.
Also, what management team is going to ask their developers to work on two conflicting features in parallel? It's a people matter as much as it is a technical one.