I think this is balderdash. There have been plenty of games in otherwise niche genres that have, whether through some measure of quality or hype, managed to appeal to gamers normally outside that demographic. Hence, 'transcending the genre' ie, appealing to people who would otherwise have no interest. Most Gaffers would agree that character action games are a pretty niche genre these days, but God Of War is one of Sony's biggest franchises, and has managed to transcend the niche appeal of the genre. RTS games tend to appeal to a select audience, but Star Craft is a mega-franchise that sells like absolute crack. Economic simulators are about as niche and specialised as you can get, but EVE Online has carved out a devoted fanbase focusing on just that (Along with space ships).
The OP is asking if the gameplay to TLOU has enough meat that to it that it would appeal to someone otherwise not too fussed about TPS games, an understandable question given the amount of praise the game has been given on all fronts. Ideally, users would be trying to ask her question by weighing up the merits of the gameplay, potential or known flaws, and leaving it to her to decide whether the game is worth it or not. It is not a bizarre question she is asking, and it's not fair that she's now being subjected to countless claims of trolling simply because she asked about one specific game. No-one gets this amount of shit in any other thread asking about the appeal of a certain game after it's released.