Is .cabal files still accepted?

the readme says:

If only the .cabal file needs to be modified, a .cabal file SHOULD be used instead of a .patch file. If the changes to the .cabal file are too invasive (e.g. removing modules, changing the structure of the package etc), a .patch file must be used.

Is this still true, doesn't look like so? At least given 111b9172 is committed recently.