As someone with reasonably good mental math skills (120+ score consistently on https://arithmetic.zetamac.com/, default settings), I cannot really say it helps me much in the real life, at least not on the surface. It sure is nice to be able to estimate some things accurately without having to resort to a calculator, but in no way would anything change in the way I think or conclusions I make if I had to use one, so there might be some truth to what Mr Wolfram is suggesting.