[almostdeadguy]

Some of the connective tissue in this article could have been better written, but I think the point of talking about isolation from a security perspective is this:

A. Privilege isolation is the hardest to refute benefit of microservices in theory, but you have to keep in mind that we need hardware virtualization to achieve a reasonably strong form of that (i.e. your k8s cluster isn't helping you out here, modulo Fargate perhaps)

B. This is rarely the primary concern when we look to microservices (or generally, modularity) to cure what ails us.

C. If we have less concern about trust boundaries, there are easier ways of modularizing code that probably solve the things we're really worried about (i.e. libraries or any other way of splitting code that is built into a single artifact).