Earlier quoted context omitted.
The theory is to incentivize awesome service by having each customer decide how much compensation to give based on the server's performance. Those who delight customers make more money, while whose who are bad at customer service make little money and are incentivized to leave the industry and do something not customer-facing.
How hard is it to bring someone a menu and then bring them the food they ask for? I don't want to be delighted by the service, I'm there for the food and people I'm there with.
Good service is knowing the menu and wine/drink list. Being able to provide recommendations and advice on what to order. Trying to write down all the orders at this table while you see an empty water glass and someone is taking 5 minutes to decide which salad to order and you know there's food for another table getting cold in the window.
If you just want food and a place to sit, there's plenty of fast food/fast casual restaurants. If you go to a place with wait staff, it's because you are going to get waited on. A good wait person can be the difference in having a wonderful night or a horrible one.