It doesn't have to be that way, it's just because our existing language facilities don't have support for what we need them to do:
"Names are regularly repurposed to point to new definitions, even when the old definitions are still perfectly valid. For instance, a library author might make a function a bit more generic by adding an extra parameter, or decide to switch the parameter order. That's fine, but the old definition was not wrong, so should users be forced to upgrade? No.
Repurposing names is fine; it's hard to come up with good names for definitions, so using an old name for a related new definition often makes sense. The trouble is that existing tooling doesn't distinguish between repurposing a name and upgrading a definition. Unison changes that..."
https://www.unisonweb.org/2020/04/10/reducing-churn/#incompa...
"Names are regularly repurposed to point to new definitions, even when the old definitions are still perfectly valid. For instance, a library author might make a function a bit more generic by adding an extra parameter, or decide to switch the parameter order. That's fine, but the old definition was not wrong, so should users be forced to upgrade? No.
Repurposing names is fine; it's hard to come up with good names for definitions, so using an old name for a related new definition often makes sense. The trouble is that existing tooling doesn't distinguish between repurposing a name and upgrading a definition. Unison changes that..." https://www.unisonweb.org/2020/04/10/reducing-churn/#incompa...