We outsource our support, but we don't really need to. We don't get a lot of support tickets, because everything "just works".
That said, it's a good feeling to have that if for whatever reason a server goes down, there's someone there to answer support emails when you have your head buried in your pillow at 3am.
It's also well invested marketing money. If you can advertise 24/7 support (and actually HAVE 24/7 support), people are more likely to sign up with you.