@stefano
Excellent writing as always!
Yes, what's optimum depends on the use-cases and workloads.
And also, flexibilities for additional optimizations are always important.

In many cases, clouds are somewhat "overkill and expensive", but for ticket sellers that need to handle rushing 10000x of connections for, i.e., 5000 sheets to be sold in 1 sec. This should be promised use-cases only for clouds. Because it would handle far less connections per day (or even weeks, months).
But this applies when the same cloud provider provides quite cheap and limited loads to quite expensive extremely huge spikes in "customizable single service".