I used to meditate/imagine natural environments in the 1980s and while in them, I'd move my perception through, looking for entities to talk to. I didn't know the term tulpa, but the notion of a spirit guide or totem is similar enough. It was better than full on dreaming, but wasn't lucid dreaming either.
Some of my friends had the shared waking fantasy that they could do things like mentally cause the traffic lights to change. I don't remember what they called it, but being public about it seems to be wrapped up in notions of membership and the ingroup.
I wouldn't be surprised if variations of what we did in teen culture then and what the authors are writing about are somewhat universal to adolescent minds. It might be a cognitive development stage, like how young kids go through a nightmare stage.