[makecheck]

Well, one reason not to is limited hardware.

In an embedded system where memory is at a premium and you may have serious constraints on how long things take (e.g. for timing purposes), the ability to hard-code an address or have it entered in some way saves you from having to support an entire DNS layer in that system.

[ghayes]

I think the joke is that DNS just hides IP addresses, it doesn't do away with them. No IP address = no DNS.