I assumed the readers would follow the link to see the original results. GMP is undoubtedly the state-of-the-art of arbitrary-precision arithmetic. The point of this table was to compare bignum implementations provided by different languages, so programs that use GMP bindings are excluded. Probably it would make sense to include the best result that uses GMP, but I think GHC is quite representative of GMP's performance.

I'm not the first one who draw such a comparison. This article goes into some more detail: http://www.wilfred.me.uk/blog/2014/10/20/the-fastest-bigint-...