It took me about 5 minutes to setup Pusher and for that I get private channels, presence, someone to handle the scaling etc... as djb_hackernews already mentioned.
We outsource DNS, email, hosting infrastructure, anything I possibly can which isn't core to the product itself.
The other side of the coin is that you now depend on dozen of external services that could go out of business one day or another. Note that I'm not saying that what you're doing is wrong, but that everything should be pondered