While reading What is a good system for a political espionage game?, I saw the system-for-setting tag, and I don't see the difference to a tightly formulated (i.e. correctly asked) game-recommendation question.
It is currently used 5 times in total, 4 of which are also tagged game-recommendation
- The aforementioned What is a good system for a political espionage game?
- I want to run an RPG inspired by Monáe's 'Metropolis' concept series
- Alternate class system for MtG inspired setting
- System for Setting: Misfits
- System for Setting: Joe Abercrombie's The First Law
The last two questions were both asked by gomad, and he added the tag to both questions in Sept. 2011, which means the tag might have missed some game-rec-reforms and -metas.
game-recommendation questions need to be specific, with the asker clearly stating which part of the game is important to him and asking for a system that has mechanics that supports this kind of thing. This is not much different from specifying a setting, though potentially less precise ("Interstellar space warfare, where the players are working for the underdog faction" vs. "Star Wars Rebels").
In fact, many game-rec-questions are about recreating the feel of a specific movie/TV series/book/...
That being said, I doubt that the tag has any merit and vote for burnination or synonymization.