The highest level of isolation for an application can be achieved by adding a new physical machine or bare-metal server, so that there's a server with its own operating system that's managing all the system resources. This was a regular occurrence in legacy applications, but it isn't practical for modern applications. Modern applications are massive systems. Some examples of these systems include Amazon, Netflix, and Nike, or even traditional financial banks, such as ING. These systems are hosted on tens of thousands of servers. These kinds of modern applications demand ultra-scalability, so that they can serve their millions of users. For a microservice architecture, it doesn't make any sense to set up a new server, just to run a small service on top of it.
With new CPU architectural breakthroughs, one of the...