Saying that they should run on kumsufi is like explaining to a wholesale company that they should use motorbikes instead of trucks, because motorbikes are cheaper.
Kimsufi is still dedicated hardware (however low-end) that costs 1 figure instead of 5/6. For normal server-grade hardware it's just 5x cheaper than AWS, not 20x.
Again, you're arguing for motorbikes instead of trucks because they are cheaper. Noone care about that, trucks were not selected based on costs in the first place.
We've been taught to build distributed system with unreliable componens and temporaral JIT eventual consistency.
Of course we can run production cloud-scale operations on unreliable systems. And single power supplies without ECC or RAID is pretty low on my list of things that cause outages. Most big hadoop/cassandra shops are running without raid and without redundant power.