And python doesn't? It has bignum, is that inferior? It is also arbitrary precision. Seems like to claim javascript has "sufficient" numerical properties would be better than claiming it is far superior to python. To do otherwise seems like FUD
Thus I claim the Python approachbiss till better in that specific area.
I don't know Deno's source for their claim. Certainly relevant is what area of Maths you're looking at. For instance looking at reread rations for vectors and matrices might be relevant for different maths problems. The functional approach in some of these things also might be interesting for some Maths problems ... broad topic :)