Yes, good idea. We should all go in together to build our own datacenter in The Dalles! Who's with me?

(More seriously though: the real challenge to this approach is that cloud compute resources are a game changer and they can be at best approximated with the high-latency connections of hundreds of distributed users. The problem to solve goes a bit past "everyone should host their own email..." And even that is a tall order if you want your email to actually be sent and received and to not drown in spam).