Opinion pieces are fine, but if they purport to say something about the world what they should be based on evidence. If I reviewed a Disney movie and said it was good, that would be my opinion, if I said it was one of the last animated films that would be produced, that would be a fact about the world and I should probably explain what I mean by that and how I know it. To more directly tie that analogy to my criticism of this article, I feel the author says that this is the twilight of the celebrity chef but doesn't really back that up with evidence.
I did see the reference to voodoo doughnuts, but I don't think it matters much. Voodoo Doughnuts and a few other places are unionizing. Okay. Is this more or less unionizing than in the past? How do unions affect "Imperial" chefs? Couldn't I have a union restaurant and still celebrate and elevate the chef? Using cinema as an example, I believe there are unions for actors and cameramen and movie editors. That doesn't mean we can't have auteurs and movie stars.
I agree that this is not a great piece but I disagree that this is well sourced. I don't think the sources or examples really prove the point the author is trying to make.
If imperial chefs are declining, let's define what an imperial chef is and count them over time. If you can't do that, let's propose an estimation method. If you can't count or estimate the count of imperial chefs, I don't think you can credibly have an opinion on their decline because it hasn't really been established that they are declining.