But it's sort of like living in a world where modern medicine has been discovered, and celebrating that one city has started moving away from leeching to treat fevers, while every other city is still practicing it, and that one city still uses leeching to treat many other diseases. Strictly speaking, it is an improvement, but....
I was going for, let's quit bloodletting, but let's also not celebrate how we're occasionally no longer bloodletting, because it's still embarrassing how far behind modern medicine we are.
Could you please elaborate on what "bloodletting" and "modern medicine" represent here?
We have languages like Rust and we have proof tools like Coq which can be leveraged to become more memory safe or more provably correct... using those tools would be like using modern medicine.
I don't think the analogy is really that great because those tools are still incredibly immature in terms of actual usability.
If you absolutely need speak in parables, do it with something that represents an earlier common practice, for example with producing houses with hammers and nails instead of modern pre-fab concrete blocks. But even that is stretching it a bit too far, the productivity difference simply isn't comparable.
Of course, some people did bloodlet for reasons that didn't help, but without knowledge of bacteria, many were just trying their best with what limited knowledge they did have.