Yes, but from what I have read about fiber optic systems, that MOST fiber systems have other components tied in, other types of cable, not just fiber. There are NOT many truly all-fiber systems in the US.
I know this because I did an extensive research project on it for school, I also work with it almost every day, and unless you are on an all fiber network, you can get some bottlenecks just like any other type of network. The "weakest link" thing, meaning if you have fiber connecting with a T1 line somewhere it is still going to slow down to the T1 speed at that point, for example.