Going to have to thank Clarste because that post was essentially exactly what I'd say.
This is why Gensokyo is portrayed through a wide variety of different lenses. Even if, say, we only had one book outside of the games for canon material, that's still better than seeing Gensokyo entirely through the games, which for the most part shouldn't be taken literally at all. This is why we have CoLA: a composition of small seemingly insignficant events with hidden gems of importance viewed through the eyes of Rinnosuke, a half-youkai(!) who can't fight, runs a small shop, talks to people, and tries to explain things he experiences entirely through his perspective. This is why we have SSiB and CiLR: two respective halves of the same story, currently Gensokyo's only serious plot that doesn't revolve around beating each other up and instead concentrating on the way characters think and behave. SSiB being a manga gives the reader a clear view of events, creating a mostly-objective viewpoint, and CiLR is extremely detailed and fleshes out everything that isn't actually shown. This is why we have the Three Fairies trilogy: a manga using the three fairies as perspective in a similar way to CoLA, acting as background observing devices who like to go investigate some of the most meaningless things, in order to give the reader a visual account of events for anything ZUN whimsies to show us. Importantly, there is very rarely any distinction drawn between mundane events and important events, because the fairies just don't care. This sort of character bias can barely even be called a bias.
This is also why we have another more dramatic manga, interviews and newspaper articles, more interviews and newspaper articles with two writers, a documentation of characters by a biased human that doesn't know much outside of their own interaction but has essentially lived super long, another documentation of characters by a biased human etc, a debate between several parties meant to reveal the sentiments and stances of their larger groups, and a collection of spellcards described in real terms instead of game visuals along with little notes about mythologies and whatnot.
and then we take all of that and we just make a lot of porn
