It actually would! There are a handful of base-10 arbitrary precision arithmetic implementations in the preprocessor[1], and modern continuation-passing style macro metaprogramming[2] makes it straightforward to write a function like factorial once you get the syntax and semantics down.

Libraries like Boost.Preprocessor can’t be taken as an example of “cutting edge” preprocessor metaprogramming. It set a very low bar, and IMO has stifled a lot of developer creativity.

[1] https://github.com/rofl0r/chaos-pp/tree/master/chaos/preproc... [2] https://github.com/rofl0r/order-pp/blob/master/example/fibon...