Eh? The Story mode of FO3 was just as linear, if not moreso wasn't it?
In New Vegas you can break off and join the legion/NCR/House much earlier than the 'last mission'.
I meant New Vegas railroaded you down a path regardless of whether or not you wanted to do the main quest. Also "four different story paths that may include one different quest compared to the others" does not equal "less linear." Also I didn't say "last mission," I said end of the first act. Or almost end, anyway.
Now granted, Fallout 3 is guilty of having a linear story, but at least there's some branching paths (which New Vegas basically doesn't truly have) and, most importantly,
things to do and discover while you're walking to your destination.
Basically, New Vegas forces you down the path of the main quest whether you want to or not, but in 3 once you exit the Vault, you can totally go in any direction and be able to survive. In New Vegas, you go off the path and there's an 85% chance you'll run into enemies far more powerful than you, and you die. You can't go off that path until you're around level 20 or so (which, depending on your playstyle, can take between
15-30 hours).