In my mind it's not a black and white issue. There are a lot of variables and contributing factors. While a number of people take advantage of CERB, in general it can't be the sole reason restaurants have problems filling positions. The whole dine-in industry is a joke. You have line cooks and dish washers slaving away in a hot kitchen making minimum wage or a few bucks more, getting treated like shit by greedy entitled servers who are impossible to appease as manager. You either haven't given them enough tables, or you given them to many tables, and once they make their money they just want to get the fuck out the place. Now being a GOOD server can be difficult, and it's a different skill set then a dishwasher, but I can tell you most aren't humble people that say "without this dishwasher slaving away making peanuts, I wouldn't be walking out of here tonight with 200 bucks cash in my pocket from tips". The problem isn't the back of the house staff are saying to themself "why wash dishes until 3am in a hot kitchen for minimum wage being treated like shit by servers when I can collect CERB?" The back of the house staff is saying "why wash dishes until 3am in a hot kitchen for minimum wage being treated shit by servers, when I can work a easier job with better hours for the same money?" Some even realize "Hey, if I'm going to work like a dog, I might as well go get a factory job that pays way better".
Now onto the next problem, the dine-in industry is in trouble. Adolescents don't go to restaurants anymore. It's all skip the dishes and uber eats so severs aren't making the money they used to when restaurants could bank on certain times and days being packed. So now your seeing less people wanting to serve because the money isn't what it used to be.
Only the good dine-in restaurants are going survive. The industry in general already had one of the highest rates of going belly up, and it's only going to get worse.