That is simply not true. An educated person with minimal programming exposure can readily pick up modern Fortran programming in 1-3 days at a pragmatic level.
Did you mean, "Julia never found any widespread adoption and remains an obscure, niche language"?
Fortran was the world's top programming language until the new millennium and is still among the top ten most popular. Arrays in Fortran can start from any index; the default choice is 1, which can be overridden with literally one keystroke: 0.
No, you can still trust compilers: 1) The hand-tuned BLAS routines are essentially a different algorithm with hard-coded information. 2) The default OpenBLAS uses OpenMP parallelism, so much speed likely originates from multithreading. Set OMP_NUM_THREADS environment variable to 1 before running your benchmarks. You will still see a significant performance difference due to a few factors, such as extra hard-coded information in OpenBLAS implementation.
Fortran has officially had the concept of modules for 35 years, which just made its way to the C++ world in 2020. It's the people who cannot update and sync with contemporary technology and remain stuck to COMMON blocks.
As someone who has been using about a dozen programming languages over more than two decades, I completely disagree with your experience, some of which appear to be due to incomplete knowledge of the Fortran programming language, including your statement "lacking in standard IEEE numerical things such as a function to check for nan". Everyone talks about C and C++, but we all know in our hearts how terrible the syntax of these languages is.
The "Hiring Fortran programmers is risky" argument is incorrect. This is, in fact, the whole point of Fortran, that anyone as dumb as a rock "would" (not "could" or "might") write performant code. There is currently no other language that can achieve this. Any other language claiming this capability is essentially recreating Fortran (perhaps with a slightly different syntax). Fortran Standard has been pursuing this sole goal for 70 years and has become extremely good at it.
Your argument applies very well to C++, though. But it's not too hard to catch a novice there, either.
This process of language love and hatred over a short period is what's called language fad. Ten years ago, people wrote articles praising MATLAB over established languages. I do not recall any of those writings ever mentioning Matlab's licensing as an issue. MATLAB is now >1000 fold better than ten years ago. Yet, the new generation throws it under the bus daily because it's not their favorite. Change is the only constant in the world of programing fashion and language fads.
The hard line limit length is at 1,000,000 characters not 10,000.
Also, all major compilers currently have flags to significantly extend the line limit length.