See this is where people fundamentally misunderstand the concept. In the context of that issue, that story tells you everything you really need to know about Kristoff for that particular story–that he’s an associate of Doctor Doom’s. The rest of his backstory isn’t relevant to that tale, and so isn’t presented–it’s still there if people want to know more, but no point of plot, of development, of character isn’t clear because you don’t know that he’s a kid who was artificially aged and implanted with Doom’s psyche years ago. That’s not what we’re talking about when we speak about making sure you establish things for new readers.