[thezilch]

That makes zero sense. Why would you run them out of the same instance / with the same configuration? Mike is already running a second process for caching; he'd simply replace it with a different instance of Redis.

[rubiquity]

You're right. It doesn't make sense. Does that prevent tons of people from doing it? Nope.

[mperham]

Because users don't read docs. They don't understand these tools. They don't catch on that two completely different use cases require two completely different configurations and two completely different instances of Redis.