We got to learn FP via Caml Light, Standard ML, pure lambda calculus and we also had some LP classes via Prolog.
Those of us that learned Lisp did it to customize Emacs.
The first two being based lisp, and the third being what inspired lisp.
It's like saying: I learned low level imperative programming from using Go, C++, and register machines. Which, sure, but the C language was hugely influential to all of that.
Because they took lisp and added types to it; via the ISWIM language document ("The Next 700 Programming Languages") which was based off of the original lisp.
Because the lisp language family is a formulation of lambda calculus and has first class functions, unlike any other language family at the time, and that is necessary for theorem proving that is based on lambda calculus.
Because they likely prototyped the system in a set of lisp macros before writing the language (all the authors knew lisp and had taught each other it).
[0] http://www.sciencedirect.com/science/article/pii/00220000789...
[1] https://archive.alvb.in/msc/11_infomtpt/papers/the-next-700_...
Says someone 35 years later. :)
Probably every (commonly found) derivative example, and the majority of languages with first class functions all come from this example.
MIT introducing Scheme and those two professors writing SICP are a large part of the reason for the current functional programming landscape. Without them I believe they'd still be as niche as APL.