I think the idea that the author was trying to express was that in a spreadsheet language, you select a data range and then choose a function to perform on that data. That's the "functional" aspect I took away from my reading of it.
However, FP is not a silver bullet either. In practice I think humans care a bit less about correctness than compilers and would like some aspects of the language to be 'fuzzy' for lack of a better word. To most people "1" and 1 are the same thing so why shouldn't the compiler understand that. There could be potential for a dynamic-fp language of sorts.
[1] http://blog.sigfpe.com/2006/11/from-l-theorem-to-spreadsheet...
Ie even in Haskell as it is, it's pretty easy to add an 'if' that takes 'truthy ' and 'falsy' values like in Python. Just use a type-class 'Booly' that include a conversion function toBool.