Eyes of Nine
Everything's Fine
I am confused - why is "infinite play" the only type of play being considered for "should a ttrpg have an X rulebook"?
Again, coming back to bill91's point - Damn the Man Save the Music is best as a one shot. Microscope is best as a one shot. Those games (and oh so many others) do not need multiple books. And even if some game group decided they wanted to run a 40-session campaign of the same game of Microscope, they probably wouldn't need another book.
Similarly, you could say FATE Accelerated is a complete game in a single relatively small book. But even for a one-shot, I'd could see wanting to use at least one other source for stunts (maybe)
Again, coming back to bill91's point - Damn the Man Save the Music is best as a one shot. Microscope is best as a one shot. Those games (and oh so many others) do not need multiple books. And even if some game group decided they wanted to run a 40-session campaign of the same game of Microscope, they probably wouldn't need another book.
Similarly, you could say FATE Accelerated is a complete game in a single relatively small book. But even for a one-shot, I'd could see wanting to use at least one other source for stunts (maybe)