system
A chat on subreddit /r/me_irl
human
Once you open these air gets in and then with warmth they start going bad so that is why you put them in the fridge and why the label says so.

In case of Butter you can keep it outside of the fridge, in winter my parents do so in order to not have to wait a long time to use it.
gpt
With the butter it depends on the type. Some butters will go bad quicker and almost all will develop a different taste after just a week or so. Just throw everything in the fridge imo.