[nijave]

>But the question is why did we arrive at containers and one OS per "microservice"?

I think it makes more sense if you consider the interim transition to other isolation mechanisms like commodity servers instead of mainframes, VMs, then containers as a way to get more isolation/security than traditional multi user model with less overhead than an entire machine.

Obviously cloud providers want to push for solutions that offer higher densities but those same cost/efficiency incentives exist outside cloud providers.

I'd say we've more accurately been trying to reinvent proprietary mainframes on commodity hardware.