I'll admit, spread of the game's name and popularity did considerably rise when popular gamers on Youtube like Markiplier (him especially) started playing it and uploading their playthroughs online. But you can tell even people like Mark have a big appreciation for the gameplay, a good example being after he finished Night 5 and discovered there was a 6th Night.
And even after people got their laughs and own personal scares from it, a lot of people started delving into the game's storyline and lore. Tbh, if you really have no interest in the game as it is now, you probably won't be able to get into it at all. And the lore is something you'd have to get into yourself to really understand why so many people are into that aspect of the game.
The gameplay may be a different case though. It's not just cheap jumpscares. They're a punishment for screwing up. And the game's atmosphere, including the restaurant's design, the animatronic's designs and their appearances throughout the area, and the mere fact that you're confined to your office the entire time, having to keep enemies out rather than ever get a chance to escape it yourself, is all there to help tension and scares rise. For a lot of people this was a simple, but new and unique take on a Horror experience, and in term of gameplay, that's why a lot of people love it so much. Opinions vary though, the atmosphere and characters won't freak everyone out, and they may simply just not like the gameplay. And that's fine by me as long as you don't try to discourage anyone else who likes it.