I don’t believe this is true. Allowing more fine-grained platform tags requires updating PyPI to allow publishing them (perhaps on a per-package basis, enabled by manual request?), and packaging.tags to report them, but no reason to change the spec.
If your list of supported tags looks like ['...-win32_cu12', '...-win32', '...-any'] instead of just ['...-win32', '...-any'], then you’ll simply pick up the most targeted build for your platform. We already have ways/ideas of handling platform tags manually in builders,[1] installers and lockers.
Having some way to inject an additional tag(s)[2] for packaging.tags to return, either manually or automatically, ought to handle the rest.
It also handles the “build the most specific wheel for my platform by default” idea that was suggested, and allows setting a non-specific dependency on a package that will result in getting the most-specific files to install.