One interesting fact that supports the point of the article is that Matlab is actually using the Fortran code for its implementation of special functions https://www.mathworks.com/matlabcentral/fileexchange/6218-co....

The amount of existing scientific code in Fortran is huge and there's a chicken and egg situation (new code uses/extends old code so new code will also be in Fortran) that will lead to further increasing it!