I initially thought the same but have come around. The problem at this point is the lack of tooling that understands and supports it. You could, quite reasonably, say they should have made a different choice based on what works best with tooling today, and that would be fair; but I think that would leave us in a bit of a local maximum. My hope is that if and as it catches on, tools will grow feature and modes to work with it—just like they did to work with Git’s index.