Basically the only "stdlib" that Fortran gives you are some mathematical functions, super basic string and file operations and that's it. There are no APIs for networking, sockets, IPC, threads, etc. that pretty much al modern languages come with.

Can you write a parser in it? Sure, but it's going to be painful dealing with strings. Can you write a web server? Yes, but you'd have to link to a C library that exposes the kernel TCP/IP interface to Fortran. And so, on.

So, essentially it would be like using C without a libc: it's doable, but it doesn't really make sense.

It's a use the right tool for the job thing. Fortran is very fast, used primarily for scientific computing in various fields - not a lot of people are writing general purpose code in Fortran. Of course you can do it, but it's not a great experience and you'd spend a lot more time doing work you'd rather already have tools for.

Mine was not a statement about its stdlib or if Fortran can do something else well. Great majority of people in Fortran community are focused on numerical methods.