> can acheive the same high availability and elasticity

Maybe not, but even just a "flick the switch to go back to a dumb system" option is worth maintaining

Is it really? You would maintain an entire parallel stack built on an entirely separate infrastructure stack, with completely different deployment patterns and all the data synced? DR is really hard if you just want to fail over to another AWS/Azure/GCP region. I can't imagine what a nightmare it would be to maintain an on-prem DR standby. To mitigate a couple hours per year (in a really bad year) of cloud downtime?

Well it depends on the system, doesn't it? For filing taxes, it doesn't matter that much if there's downtime as long as you have a plan to move the demand around (i.e. don't fine people when it's down), but for 911 calls you're going to have a lot of fairly niche infrastructure that you need to plumb in any way, so the actual cloud parts should be comparatively easy to replace.

For those sorts of systems, my bet is that the DR strategy is to fall back to what they did before computers existed at all. And honestly that may be the best option. As long as you have pencils, paper and telephones then you can probably approximate what you were doing in 1995 anyway.

High availability? Certainly. Elasticity? Not as well.

The right lesson is "Be a person that strives for excellence in all spheres of life".

I've been doing "Local IT" since '96 and I spun up an EC2 instance the day I saw it announced on slashdot and have been using both ever since. Both excel in some ways in the hands of good people.

Anyone thinking "I'll move to the cloud (or to on-prem) and all my problems will magically go away" is fooling themselves. If you suck at on-prem those underlying issues will carry into the cloud. If you have excellence in a well run on-prem install you'll experience great benefits leveraging the cloud.

For instance, Last month I was discussing a "move to the cloud" with a bank CTO. They had an unreliable on-prem network and moved to the cloud.. and they just discovered after suffering an outage in the cloud what an "availability zone" was. The same attitudes that made their on-prem unreliable, insecure, expensive will make the cloud the same way for them.