Thanks for all the replies. My intent is not to suggest that folks may be
doing too much partitioning, or for the wrong reasons. I mostly just hoped
to hear the rationale behind it.
Notwithstanding that generalization, I am curious about the nature of the
alleged Web workloads, and why folks might think they need a VM which is
separate from the "production" box. We run dozens of HTTP server instances
on the same box as our production data.