Julia currently has specific weaknesses that make it unsuitable for a large category of problems that a language like Fortran (or C) has handled seamlessly for decades.
Do you have any specific example? I am truly interested. One of the things I don't like so much about Julia is its community, always preaching Julia is a better language than X, Y, and Z all together. It would be nice to have some concrete examples.
The obvious one is any time you need a statically compiled binary. There's work on that, but for now at least, that's a definite shortcoming.