Non-trivial experience in research computing support says that gfortran is surprisingly more reliable than ifort. "Just use GCC and openmpi" has worked in enough cases for me. A number of HPC benchmark lists I've seen have had failures in the proprietary lines and not GCC's.
The performance advantages are largely mythical too. The last time I ran the Polyhedron benchmarks with beta versions of ifort and gfortran on SKX with the best obvious overall optimization (profile-directed), the bottom line was insignificantly faster with gfortran. Gfortran is infinitely faster on ARM and POWER too.
I wish research councils would support the free software.
GCC has made large improvements in the last 10-15 years in fortran support and performance. Memory is long and sometimes you just learn things as a beginner which remain "true" regardless of the changing facts.
Intel Fortran was far superior in language support and binary performance in the mid 2000's and a researcher couldn't be without it.
Whatever the reason, people shouldn't be propagating the incorrect information, especially if they're in research, and if they're interested in performance, which requires measurements. The same thing needs saying over and over here and elsewhere.
I don't remember figures and dates, but g77's performance was at least reasonably competitive with proprietary Unix compilers once GCC's backend was sorted out for the architecture (scheduling in particular). It was also mostly more correct. Observationally, researchers could do without ifort, especially on non-x86 hardware -- although ifort morphed from the DEC^WCompaq compiler which was used on our Alphas. (A good deal of work was done for g77 specifically because of problems at the time with portability and availability of compilers for a high profile computational project.)
The performance advantages are largely mythical too. The last time I ran the Polyhedron benchmarks with beta versions of ifort and gfortran on SKX with the best obvious overall optimization (profile-directed), the bottom line was insignificantly faster with gfortran. Gfortran is infinitely faster on ARM and POWER too.
I wish research councils would support the free software.