I agree there is some truth in what you're saying. However, without programmer's curiosity and desire to create new interesting and beautiful languages, we would still be "focused on business" and writing code in COBOL, Fortran, C, Pascal...
I don't think that was the case for me at least. I felt like (using your own analogy) the more I studied Rust, the better I learned how to use every other hammer. Learning a new programming language helped me learn c++ better since I was constantly on the lookout for potential memory leaks and other common pitfalls that Rust prevents. Now when I code in c++, I always try to write the code with safety in mind.
I actually agree with you in general, but in this case we spent six months hammering in nails with a wet sandwich because the only available hammer has a chainsaw for a handle ("it's perfectly safe, just don't ever press the on-switch"). This blog post is me seeing something that looks like an actual hammer and suspiciously looking for a trap.
I agree with you generally -for me, given that I already know java well, it's clearly not worth the effort to spend much time on (say) Go. I make an exception here, because I think Rust has genuinely useful new ideas brought to the table.
This is the stone-age of computer science. Things aren't really going to get better at the behest of programming language luddites who think their 40-odd years of experience constitutes the whole future of technological progress.
