No, wasn’t me I’m afraid.
@knittingwithtea I think at some point @copperbadge posted something along those lines.
It wasn’t me originally (I was the canned food post) but in general it began a bit earlier, I believe, because to make jello salad you had to use the gelatin sheets or powders, and you could only use those if you had a proper icebox, which was a luxury. Before that, you had to have a chef who knew how to do it, pretty much, and they had to spend hours boiling bones.
So until the 40s or 50s, when everyone had a fridge, gelatin was a sign of wealth and upper-class aspiration. It remained popular through the seventies because that was about when kids started taking refrigeration for granted and grew up not to care about how fancy their jello was.
I could be paraphrasing or mixing some things up, but hopefully this will help on your quest!
The best analogy I’ve ever heard for the advent of powdered gelatin+fridges is that it was as if someone suddenly brought kits on the market that let average people do molecular gastronomy dishes in their own home.
Mooncustafer 