Honest question, does that matter? Ie if we say that they can do it better than i can, hypothetically that means i'll have more downtime than them - yes? If that's true for everyone, then the internet will, in aggregate, be down less with CF than if we distributed better. Assuming of course that they can handle the scale linearly, and that it doesn't cause them to have a worse uptime than if i hosted.
So the question seems to be does the internet going down at the same time outweigh the internet being down for larger periods in aggregate? I don't know, honestly - seems like a tossup.
Is there a better angle to view this from?
edit: My issues with centralization are more about privacy, incentives, points of authority/leaks/autonomy, etc. Downtime seems the least concerning to me.