The new ways come for a reason. And the new ways should respect PEP20, meaning they should work for the old use cases, so that everyone can start using the new ways as soon as they can upgrade to that version.
Now, of course Python is interpreted and packages are shipped as raw source code and this makes things harder for library authors, because were there a compile/transpile step, they could write using the new and shiny obvious ways, all the while providing compiled blobs (or transpiled libs) targeting multiple versions.
Now, of course Python is interpreted and packages are shipped as raw source code and this makes things harder for library authors, because were there a compile/transpile step, they could write using the new and shiny obvious ways, all the while providing compiled blobs (or transpiled libs) targeting multiple versions.