I'm FGO's biggest hater so you know I'm serious when I say this all began with FGO releasing in English in 2017. No longer could Type-Moon bury their heads in the sand and pretend an international audience for their visual novels didn't exist, not when JAlter sales alone made 3 million dollars.
Anyway, it's actually really cool that we can see Nasu go back and decide an actual intended reading order for Type-Moon works. Mahoyo was written first but never released to the public, Kara No Kyoukai sold like 6 copies on its first release so nobody read it, while Tsukihime and even the original Fate/Stay Night would stay out of mainstream store fronts due to being eroge, leading to readers coming in to Type-Moon almost entirely through (often troubled) adaptations and never the source material.
But it doesn't have to be like that anymore. Mahoyo got remade in 2012 as a VN, Fate/Stay Night got rereleased as a mainstream commercial work on the PS2 with Realta Nua, and Tsukihime got a Remake for consoles.
So it's pretty cool that Nasu used the first official English (and Simplified Chinese, they're an even bigger market tbh) translations of his novels to make something of an actual reading order.
Do you want to get into Type-Moon? Read Witch on the Holy Night, it's simple, has no routes or choices, and lays all the basic foundations of the setting. Tsukihime: A Piece of Blue Glass Moon then elaborates on the monsters and the militaristic Holy Church that Mahoyo introduced. Finally, Fate/Stay Night rounds this out by going back to the mages, getting deeper into their society and while introducing a whole other kind of monster in the heroic spirits that became so iconic to the entire otakusphere.
It doesn't have to be hard and inaccessible anymore! We're so fucking back