You're right, this should have been thought of earlier. The thing is that cosmology is hard, and science is driven by personalities and consensus. It can be h

You're right, this should have been thought of earlier. The thing is that cosmology is hard, and science is driven by personalities and consensus. It can be hard to break through. Timescapes has been around for a decade but only now it's getting attention -- why? because there is a sea of stuff to pay attention to, a lot of not-even-wrong stuff, and a lot of inertia in the current consensus. In particular very few people really know GR, and it's hard to apply it creatively, especially if that means you need new solutions to the Einstein field equations -- that can be a real pain to deal with.