I’ll change my opinion only once we’ve actually got something working reliably for a while. There are a lot of open questions, and remember that we don’t only need to support conda-forge - building wheels for PyPI is the harder and more time-consuming part, and AFAIK no one has even tried to build any redistributable wheels with Flang. It may or may not work at all, it may increase the binary size due to the extra vendored runtime, etc.
I’m afraid that this will never be true unless Microsoft and Apple start shipping a Fortran compiler or runtime. To give a very concrete example of the type of problem Fortran causes that C/C++ do not: right now we’re considering dropping support for macOS 12 wheels in our next release, because we’re using gfortran from Homebrew and the deployment target was bumped too high by Homebrew. For C/C++ you can support older macOS versions very simply, by setting the MACOSX_DEPLOYMENT_TARGET environment variable. For Fortran on the other hand it’s intrinsically hard, you have the choice between using a compiler someone else built and lose control over what you can support, or maintaining you own build of a compiler.
We have burned huge amounts of hours on stuff like that (hard to estimate how much exactly, but many hundreds of hours at least by SciPy/Numpy maintainers, possibly 1000+), and that’s effort that could be better spent in other ways.