For example, can we ask: Why did Kai W leave DigitalRev TV?
My gut is instinct is that this type of question is a poor fit for any Stack Exchange site. "Why did [social media personality X] [do action Y]?" just doesn't seem to work well into Stack Exchange Q&A. To me, they feel gossipy (even if there is an objective answer).
But going beyond my gut, in my opinion this particular type of question has nothing to do with photography (in the sense of being on-topic for Photo.SE). That Kai changed employers is of no interest to the art, science, tools, or business of helping people make or understand photography. People might be personally interested in Kai's goings-on, but that interest does not intersect the mission of Photo.SE, in my opinion.
Answers to those questions are either:
Opinion-based. Possibly opinions can be backed up with citable references, but still largely opinion-based. Definitely not a good fit for SE sites.
Objectively answered. But in most of these cases, the question should probably be downvoted for being trivially searchable (the hover-over text for a question's DV button is: "This question does not show any research effort; it is unclear or not useful"). In this case, Googling for literally the question in this meta-question, "Why did Kai W leave DigitalRev TV", brings up several answers. The first of which is a PetaPixel article that embeds Kai's video explaining why he left.
This is an interesting edge case. Certainly if the question about the photographer had to do with their photography itself it would be on topic, however I'm not sure that topics unrelated to a photographer's photography would be on topic and this seems tenuous at best.
Further, this is either something that they have publicly stated or it's something that would be pure opinion. The later would be strongly off-topic and all we can do towards the former is try to find it for you. I don't expect this to be a good candidate for a question.
I would say no, this isn't a valid question on the following (extremely basic) premise:
"Does the answer to this question help anyone with their photography in any way?"
I would confidently suggest that answering that question isn't going to make anyone a better or worse photographer, nor is it "valuable" content that should be retained on a Q&A site. The content is better fitted to social media sites.
I agree that if the question is objectably answerable (that is, we can say with any degree of certainty why Kai left DigitalRev in Hong Kong and moved back to Great Britain where he is from) then it is also one of those that should be answerable with a minimal degree of effort on the part of anyone with access to google.
But we have many upvoted questions with (sometimes) highly upvoted answers that consist of little more that pointing to the applicable section of the User Manual of the camera the OP is asking us how to get to do what they want it to do.
On the other hand, the content of Kai's DigitalRev videos were very much concerned with "... the art, science, tools, or business of helping people make or understand photography." This being the case, it doesn't seem that far off base to ask "Hey, what happened to those great photography videos Kai was making at DigitalRev? Why did they stop?"