Whereas as long as you e.g. "keep it postgres", you're able to experiment (at fairly low effort) with different database setups and find what is more efficient or cost effective for you. If Cloud Provider X's pricing model starts to deviate from what people are able to achieve with some custom database setup, people will start flocking to that - and, in fact, Cloud provider X would probably find themselves competing with an easy to use "managed database" service that does just that on their own Cloud Marketplace.
Not that this isn't an extremely interesting project as long as it's possible to wrestle the concept free from Amazon's infrastructure.
- Purchasing the kit and waiting for delivery. Probably a few weeks BUT that's a few weeks of no extra work on your part, just waiting. You still need to fill in the PO, get it signed off by your CTO, whatever
- Racking and powering. Except on the biggest jobs, 1-2 days for a DC team of physical labour.
- Installing an OS and software. These days, a few hours, PXE boot then let CFEngine or whatever do it
For everything else, you still need someone to either do it or take responsibility for it being done and verified and documented and reviewed to see if it's still the right solution and so on and so on. As I always say "if you don't have a DBA then YOU are the DBA".
Incidentally "you don't need a DBA anymore" was also the pitch of MongoDB et al... Careful devs, one day it will be your turn :-)
"Now you can trade not having a DBA, and letting your programmers not get criticized by him for paying us $$$($$$$$$$$$$$$$$). DBA's bad ! Bad ! BAD I tell you".
I fixed a customer's database a few months back. It was a cloud sql instance. They paid cloudy provider $40k for hosting a ~130 MB database (in ~ 8 months) before getting a consultant to look at it. I charged them $2k for an afternoon of hacking onsite and 2 days of followup, and they were ecstatic to pay it, saying that not doing that for 2 more weeks would have been more expensive. They're now paying the minimum charge for that and 5 other databases.
Most of the cloudy database offerings are ridiculously expensive for small, infrequently accessed databases (0.1 to 0.01 qps, let's be honest there's a boatload of these in every company), compared to either hosting it yourself or getting a small shared hosting or dedicated provider to do it.
I often wonder if a lot of the cloud scaling isn't being pushed by these companies for the same reason. Using a distributed publish-subscribe queue will seriously slow down anything that doesn't require, say ~5-10 machines, to execute.