Which is more likely to suffer an outage? Which is more likely to suffer a long outage? Which is more likely to suffer a fatal outage?
I had shared hosting with a provider; mistakes and bad management lead them to, basically, kill my account for most of a day - including all my sites.
Which sucked.
Since then I've been moving to my own VPS's - currently using two shares from Gandi to host sites, provide my own DNS and so on. I actually tried this a while ago and it got bogged down in complexity; now powerdns, nginx et al are much much simpler and it's only taken me a couple of days to roll out.
To be honest; I think with cloud services becoming so much cheaper we will see more and more of this - with us relying on "hubs" for our infrastructure rather than our front facing sites.
But your criticism is completely baseless if the average downtime on a central hub is less than the average of a self-hosted solution.
Frustrating, but that's the way it is.