As far as vendor lock in, in general not just with respect to the cloud, there are so many path dependencies and the risk of disruption versus the reward is so rarely worth it, it hardly ever happens.
How much would Oracle or Microsoft have to raise their prices on their database products for instance to make it worthwhile for a large enterprise company to move away from them to an open source alternative?
I agree with the general sentiment that optimizing for extreme portability does not make sense- but there is a balance that needs to be struck. Designing your apps to be relatively SQL agnostic, or at least isolating those dependencies, makes a lot of sense.
What about all of the programs that you used that depended on Oracle specific drivers. Even in a perfect world where everything was using standard SQL, would the regression testing and migrations be something you would want to tackle as a CTO? Would you be willing to take the reputational risks of something going wrong?
A mature service mesh will let privileged users get inside containers to attach profilers and debuggers, manually as needed or systematically through performance monitoring tools, in situ or with temporary exclusion from the load balancer pool. It's also sometimes necessary to correlate issues with host-level metrics to understand weirder bottlenecks and tail latency issues.
> it rarely happens
The credible threat of it happening keeps prices low enough to make it unnecessary.