To me, this seems to have at least two implications:At least to me it is not really not about advantage, at least not mainly. I think the point of roleplaying is to get immersed and inhabit a viewpoint of a fictional person, and part of doing that is to accept that this person will have different amount of knowledge than you the player. If you're incapable of doing that, what's even the point of playing?
(1) It doesn't matter whether or not the player has their PC use fire on the trolls. One player decides that their PC heard a story in a tavern from an old-timer and uses fire; the other player decides that their PC is ignorant of trolls and just plinks away with regular arrows. Both are playing their PCs as they conceive of them. And no harm is done.
(2) The classic D&D monsters with their baroque immunities and vulnerabilities are basically otiose in this sort of play. Those monsters were invented to challenge players, and to force them to learn different winning formulas, Over time (and perhaps over the course of multiple PCs), players would improve their knowledge of the game elements - trolls, ochre jellies, yellow mould, etc - and be able to defeat them more handily and thus do better at the game. (This is a point that @hawkeyefan has also made.) Once play is no longer focused on challenging players, such that the notion of "unfair advantage" doesn't really apply, why do we bother having all these different trick monsters? They've outlived their usefulness.