For web dev, I would rather have an expert in rust obviously, but I would also rather have an expert in php who expressly choose php over rust for the sake of the kiss principle. Plus he would probably be satisfied with a lower starting salary :-)
But you are right, reality often goes differently than what's thought to be ideal, which is why "perfect" solutions sometimes doesn't gets adopted in favor of a less perfect solution, which leaves the old "perfect" solution forgotten by history.
But you are right, reality often goes differently than what's thought to be ideal, which is why "perfect" solutions sometimes doesn't gets adopted in favor of a less perfect solution, which leaves the old "perfect" solution forgotten by history.