I am not sure if they are falling off or just getting messed up.
Here in Tampa, there are a few that have moved or changed names, yet the listing on the site still gives the old location/name.
I have also noticed many that are mis-categorized. The preset area is wrong. Often here in Tampa, they get listed in MARTIN, a county that is not really close to here, yet the restaurant is within the city limits of Tampa. Messes up the searches and using the preset categorizations.