> I'm so continuously confused why Minecraft doesn't have a show-off mode where a team of people can build something, and then someone else can spectate it, without causing undue server load.
You'll be confused by Minecraft in general then. Mojang's core team seems like they never changed a bit in all these years despite becoming a billion dollar studio, for better or for worse. Last time I played it, mods can still make the game run twice as fast.