Given that famous chefs operate multiple restaurants, it's obvious that they don't actually cook the food at "their" restaurants. What you may not know is that they don't actually write their own cookbooks either. The brand of a well-known chef is so valuable that it's tremendously inefficient to restrict the quantity of stuff they slap their name on to the things they actually have time to do. The hope, from a consumer's perspective, has to be that chefs will be mindful of the potential damage to the overall brand of a bad cookbook or a lousy restaurant thus offering some quality control.
Something I wonder about is how long will it be before chef brands become completely detached from the individual associated with them. Yves Saint Laurent has two wikipedia pages, one for the person and the for the brand which he certainly didn't do 100 percent of the design work for and which persists despite the fact that its founder is dead. This is typical in the fashion world where we take for granted that the most famous labels generally denote founders, not actual designers. Nobody gets to feel robbed when it turns out that Hugo Boss did not personally manufacture their Hugo Boss suit, or even supervise its design in any respect. I was mildly surprised to discover recently that Hugo Boss was the name of a real person (among other things, the manufacturer of SS uniforms during the Nazi era)—I had just loosely assumed that it was a cool-sounding name somebody made up. This is much less standard in the food world (with the important exception of McDonald's) but it seems like the way things are headed. If Bobby's Burger Palace is a successful business, then presumably it wouldn't shut down if Bobby Flay were to die in a car wreck tomorrow. Some aspects of the Bobby Flay brand (TV shows!) probably can't be undertaken without the man himself being present, but the whole rest of the enterprise could roll onward, perhaps with whoever's actually running the kitchen at Mesa Grill or Bar Americain installed as the new official chef.