I've heard a lot of ideas regarding the speed runs, this sounds like one of the best I've heard. If philosophy tombstones dropped from mobs at a rate that gave roughly the same number (or perhaps a bit more) by the end and mythology tombstones for completion of the dungeon then people who are gearing up would farm it. People who are way past it could speed run for the mythology if they thought philosophy tombstones were useless and were desperate to farm in a hurry.

edit: yeah also the repair thing