Re: Is it comparable?
I work for a hardware vendor and everything you list in your first paragraph is instinctive for all my customers. If DHH hasn't considered this then he's not the bright chap pretty much *all* of his public comments suggest, and a massive outlier amongst his peers.
Secondly, most of these objections are handled by using a co-location data centre supplier rather than running your own. I see very few business who still own their own data centres apart from some (not all) of the largest multi-nationals. (See my final paragraph below as well). So objections like a UPS and generator are moot, as it's part of the service you are paying for. Added to which Cloud services are often run out of these third party DCs anyway.
I would also contest your argument that moving to the cloud removes a lot of corner cases that might bite you - yes, it removes some, but just introduces others. Otherwise why has SRE suddenly become a thing as the cloud has grown ?
"People didn't switch to cloud to save money, at least no one with any sense did" - seriously? More than half of my customers have, if not an "Everything Cloud" policy, at least a "Cloud First" mantra. The more aggressive/impatient/foolish ones are getting their fingers royally burnt and seeing costs go up by 50%+. IMHO it is a combination of short-term opex avoidance, the desire to be more "agile" and simply an attempt by board-level people to appear more "sexy" that is driving this rush away from on-prem.
Ultimately though this is about scale. It rarely makes sense for consumers of specialist resources to produce it themselves. Who generates their own electricity or owns their own dark fibre for telecoms? But there comes a point where it is cheaper to take over yourself, and this often brings accompanying benefits like greater control - you are no longer forced into your vendors service levels of small, medium or large, can choose when maintenance occurs, are able to cope with unusual edge-cases and so on. As you say, there is some additional responsibility to be inherited if you do this, but you pay your money and make your choice. A final caveat though - I work with large organisations who have the luxury of size to allow some redundancy in people and resources and economies of scale. I would agree that cloud makes a lot more sense for smaller businesses.