Lanefan
Victoria Rules
When I see "be a fan of the characters" my first thought is that it's quietly advising the GM to, when the chips are down and a character's under serious threat, pull your punches or fudge things such that the character scrapes through; as opposed to just letting the dice fall where they may even if it means the character drops dead.I don't run narrative games so I have only seen be a fan of the players/characters here, but my impression as I've said upthread is that it is similar with many parts of the DMG 2014, where it offers good-natured advice on GM etiquette, handling different players and their creations.
I do not think it is an expression to buck the system.
At the end of the day we should all be charitable and logical in that narrative RPGs are still games with rules and principles, and what would be the point of those rules if "be a fan of the characters" was meant to ignore those rules.
EDIT: And to be fair to @Lanefan and @Maxperson's comments there is indeed a conflict of interest, how can there not be, I have spent months and years with these characters... frankly I do not know how a GM isn't a fan of the PCs at their table after some time.
That's not neutral.
Also, "be a fan of the characters" means, in effect, cheer for them; and when you're the one providing the opposition this puts you in the rather bizarre position of cheering against yourself. And sure, this means you get to cheer if you win and cheer if you lose, but it does seem somewhat counterintuitive.