Why do they keep saying never to leave anything out for more than 29 seconds? Why are you supposed to instantly panic and immediately shove everything in the fridge?
Partly to check, I regularly leave food out for 24-48 hours and eat it normally. Never caused me the slightest issue. By contrast, I have caused myself an issue by improperly washing dishes.
Cooking sterilizes. If you leave food out, it will gather the most opportunistic organisms from the air - the ones that find it most delicious. Indeed the pre-industrial way to gather baker's yeast is to wet some flour and leave it out in a dish. Thus, the stuff that lives on old cooked food is exactly the stuff you need in your gut to digest it thoroughly.
They want to lay waste to your symbiotic gut flora by over-prescribing antibiotics, and then do everything possible to ensure it can't come back.
You would think they don't understand the biology well, but intent matters. Intent matters a lot. They intend for you to be unhealthy, and their actions always line up with this goal.
P.S. Baker's yeast is delicious. A bit musty, sure, but it's a good must. I use it like pepper sometimes.
Marmite is yeast extract. Why bother extracting it?
Fun thing I accidentally discovered: guzzle fruit juice, chase with spoon of yeast. It fermented in my stomach, because the juice dilutes my stomach acid enough to avoid killing the yeast. Interesting sensation.