In fairness running a restaurant is nearly a round the clock job. Running delivery and the online reservations is more. Managing reviews is even more. I agree

In fairness running a restaurant is nearly a round the clock job. Running delivery and the online reservations is more. Managing reviews is even more. I agree that its hard to believe one restaurant hasn't tracked it yet but I think its more a confluence - are you good enough/ no dip in performance that you can claim this correlation or are you confident enough to go out saying that knowing you have to defend against ppl saying "well maybe you just suck now!" - did you have time to screenshot it when it was happening aka the day Yelp called and your dishwasher was out sick and your supplier of eggs upped their price - how long does the business even run. lots of restaurants close down and Yelp is not on a top ten list of concerns - if you're established then your focus is growing business not dealing with the mafia. maybe you pay them, maybe you double down on other channels like uber eats or a new location or whatever.