It seems that the primary usage of these terms is either:
mutual mystification of contractors and/or clients who don't know what they are talking about or how to talk about it,
the innocent and ignorant (see this question) , or
laziness to avoid having to say user-interface/user-facing or business logic/database/infrastructure.
Granted, you don't always want to explain to the boardroom what the aforementioned terms mean. Is that justification for adding confusion by using these terms to generalize and mis-generalize all kinds of technologies?