I think #1 comes from a rumor that Archer's timeline is the Illya route (which isn't true as Nasu said Archer's timeline can't be any of the routes). It also goes in chronological order - Archer's timeline was the one seen at the very beginning of the prologue when starting a new game, then the Fate, UBW, and Heaven's Feel routes all have to be played in that order, then Prisma Illya and the alternate timeline with Miyu came after.
