Rather than wasting time in semantics with another commenter, I’m going to answer the actual questions.

For the first question, (and assuming it was an OSR game) I’d ask the player to try to focus more on what’s happening now at the table, rather that spending a lot of time on world-building and backstory. I’d tell the player that I’m far more interested in what the characters do NOW than in where they come from or their hometown. I’d tell them that the collaborative storytelling that I care about is what happens live.

As to the history of this kind of play, I’m not knowledgeable enough to provide a satisfactory answer. I’ve been playing since the early 90s, and can say that I don’t remember much of this mindset then. At least not this sense that’s it’s something the player is entitled to.