My reaction: Functional programming fits well with both the Unix philosophy and the web architecture. When your modules/functions do not share mutable state, there's often no reason to smoosh them all into one huge program.

Portions of Amazon and Google are written in functional languages or styles, but in a well-designed system you often end up with many smaller programs and no larger ones. Also, there's no strict requirement for one program to be in the same language as any other.

"Big" should never be a goal in programming.