World Record of a Death speedrun... what is this world coming to? x_X
More like a sign of when someone has way too much time on his hands (likely a him). I'm okay with black humor but I draw the line at death and corrupting innocence (in regards to harming children's toys and the like).
In this case, it's simply a side-effect of speedrunning conventions that were determined by countless other games before this one - the idea is to reach whatever is defined as an ending as quickly as possible, and in this game, that's how it goes (speedrunning of more open-ended titles typically gets more confusing than this - see Animal Crossing for an example, where
the current 100% world-record is 19 hours, 25 minutes, and 35 seconds).
If there was some glitch that can cause a skip to some other form of ending (or the credits, but I don't think that this game even has any), people would be aiming for that instead.
In the absence of that, there are actually
two speedrun categories for Tamagotchi GB: Death%, and Mametchi%. As you can see, one is much faster than the other, thus is competed at more.
I still wonder why on earth they didn't fix the math minigame with its terrible controls. Perhaps you're only supposed to direct the tama when it is moving near a card instead of when the next round has started, but I never had the instructions and the in-game ones are unhelpfully hilarious.
My understanding of this is that you can really only prompt them as best you can, but they'll still sometimes make their own decisions and those will sometimes be wrong. Holding the d-pad in the direction of the correct answer and and mashing the A Button seems to work best for directing them, regardless of their distance from the answer, in my experience - though that gets tougher towards the end of a knowledge contest, when there are something like eight answers on-screen at once!