It is a new package. From a practical perspective once you break backwards compatibility the new major version is its own independent thing. If you pretend its the same thing then you run into the situation where two libraries need v1 and v2 and therefore can't coexist. This is going to destroy your entire ecosystem. Replacing a few strings is nothing in comparison.
Not saying its right or wrong, but clearly it is not a death sentence.
Linux distros have the same issue, rpm or .deb packages cannot have the same name but still support having 2 versions of a package/library installed.
If it's a shared library and they don't get the SONAME versioning right for incompatible backwards compabiliry, it's even more cumbersome, and incurs more work for everyone to consume that library.
That perspective isn't appropriate to use outside of a narrow scope. In particular it's not appropriate to use at an ecosystem level, it's too surprising.