I took biology in 1996; it wasn't a thing yet. Someone else claimed it was already widespread by 2001. I don't think I encountered it in the wild before 2005, but it could have been much later than that.
KnowYourMeme suggests the phrase originated in a textbook from 1957, but it didn't reach memehood until 2014.
I think it's just the most simplified you can get talking about cellular biology, specifically when teaching organelles. So most primary science textbooks use that terminology and it's more memorable than all the other organelles so it just stuck and it got repeated and reviewed every year and it sorta became a pre Internet meme and part of a shared consciousness if you were schooled in the US.
We actually had the same sentence as the headline for the chapter about mitochondria in our class in the late 90s, just translated. "Mitochondrien - das Kraftwerk der Zelle"
The exact origin of the symbol (cool S) is unclear; however, it is generally considered to be an artifact of childlore, meaning that it is taught by children to children over the course of generations.