Where did this idea come from and why is it so often claimed? Never in my life have I heard someone use 'jealousy' in that context, yet it seems to be widely accepted fact on the internet.
If you're not aware, "literally" also now literally means "figuratively".
It's memes all the way down.
Modern, and especially colloquial, usage tends to be as a synonym of “envious”, so far as I know. “I’m jealous of her hair”. “His Instagram posts of his beach house make me so jealous”. “Stop mocking her car—you’re just jealous”. I don’t think I’ve ever heard or seen the older meaning intended in colloquial speech or all but the stuffiest of writing in the last 20+ years.
So, as is typical, two useful words have become one word through misuse.