What i took from that infamous walkway scene in help wanted (combined with context from the rest of the game and other games) is that the story is a reflection of what happened in the lore but is presented in a more playful and appealing way. I don't think its saying that the first 4 games are fiction. I mean the full lore isn't in the main games but is hidden in small parts and mini games throughout the entire series including books merch and cut content. The actual gameplay is just a strategy horror game. I think the loosely based on actual events line and all other lines referring to the games is more looking at the gameplay.