The only non-replacable thing on my development machine is the code. It makes more sense to me to always push my feature branches up to the server, which is backed up, than for each dev machine to be backed up separately.
Backup is good because it's automatic. Saving somewhere else is nice too, but it's not really backup.
My point was that pushing constantly as a backup mechanism isn't an option if you intend to rebase frequently (unless you're the only developer on the project).
The D in DVCS is all well and good, but there are business reasons for having a canonical store of all source materials.
Come at me, bro.