My understanding, and this is from never playing it just kind of absorbing info over the years, is that there is an almost final 'boss' of minecraft (unique monster) that is buried as deep into the game as possible. Speed running it is routing the best way to get the materials and weapons you need to access it and kill it
Also no idea what sort of restrictions they have on the world that's generated but I imagine there is some element of luck
yes that is what you're talking about
---
Born to bear and bring to all the details of our ending To write it down for all the world to see