Bollocks. I've had two machine failures in eight years, versus at least 20 network failures. Sure, maybe the network admins at five different companies I've worked for all just happen to be a bunch of muppets, but I highly doubt it.
That's your privilege. I don't. The only time I remember the network going down was after a complete air conditioning failure in the server room (a highly unlikely event in itself, but not IMPOSSIBLE) which forced a complete shutdown of IT services. And even then people could still work. Sure, not as well as usual but working was possible. The last time a machine failed was .. oh right. Yesterday.
Also, get better machines. The last time a machine failed at this all-macbook shop was several months ago.
In either case, you will lose unpublished work in the event of a catastrophic local drive failure.
Only in the case of a centralized system, you will also be unable to work unless the entire network path and remote server is available. This will almost never be a question of data loss but it means that you will be unable to perform version control operations until it's resolved.
(1) If this doesn't apply to your office network get a better network. Now.