I think the utility of it looks more like a step function than linear - the moment you introduce ads, the incentives start to spiral very quickly against the user's interests and I see no way to offer the best of both.
I've said for years that if something like this existed, I would pay for it, and a few people (not all) have agreed. It's basically a test of that, and if it's completely untrue, that's fine, but I'm also very happy with it not being mainstream or particularly profitable. As long as server costs are covered and I and everyone else is getting the UX they want out of it, it's fulfilled its mission.