This is only partially true. Steam has an offline mode (you should activate it at least once), which works fine. I usually play on long train rides, so it is a feature I use rather often. Most of my single-player games work without internet, if not, they usually have third-party protection like securom (pro tip: don't buy them).

If Steam crashes, SteamWork doesn't work (Cloudsync, Matchmaking, etc.), but thats like any other master server crash. Also, SteamWork syncing is true syncing, so you have all your game data on your device and accessible. Its not like Game for Windows Live where you have to be logged in to even access the save games on your computer.

Say anything about Steam, but they are pretty far ahead in the 'user-friendliness' department.