Increased VFR limits and VFR on top for non-EASA licences does not mean the IMC rating is valid outside of UK airspace and CI. The CAA alter your PPL privileges, and these are applicable worldwide.
Semantics. It is because you have an IMC rating that you have these additional privileges, which are very useful, and historically another important reason for the IMC rating. In other words not mentioning this element fails to give the entire picture.
Legally, the IMC rating can be used outside of UK airspace with the consent of the national authority, but in practical terms no other country has given that consent or is likely to do so.
I know of cases where another country has given consent.