Linux

Not sure if you're being sarcastic or not, but the point of this is to reduce overhead associated with virtualization (aka VMs). Few workloads are able to take advantage of the massive compute resources that a single beefy machine has, so partitioning it is the most efficient use of resources, especially in data centers where maximizing efficiency is important.

Why keep ten machines when you can do the same job with one?

Sometimes you have different use cases. One beefy machine is likely more energy efficient. Many small machines allows reuse of old hardware.

I wish we'd get a proper microkernel, instead. If we're going to accept some performance degradation, let's get some benefit from it.

Again: I have high hopes for Redox.