> ...prevents experienced engineers from quickly learning it on the job
The problem is in the longevity of Fortran. The variety of codes accumulated through time makes up for more than one Fortran. Modern Fortran may appear as a new language, yet still very compatible with 'classic' Fortran. MPI adds another dimension to learning it, though there's tooling around it.
The aspect of tolerance to single letter variables and cryptic function names could also be a factor, no kidding.
In general, asking for prior experience with Fortran is reasonable, just as hiring someone to "quickly learn" C on the job is quite non-pragmatic.
The problem is in the longevity of Fortran. The variety of codes accumulated through time makes up for more than one Fortran. Modern Fortran may appear as a new language, yet still very compatible with 'classic' Fortran. MPI adds another dimension to learning it, though there's tooling around it.
The aspect of tolerance to single letter variables and cryptic function names could also be a factor, no kidding.
In general, asking for prior experience with Fortran is reasonable, just as hiring someone to "quickly learn" C on the job is quite non-pragmatic.