Why do you think people go to restaurants when they want to celebrate something?
People go to a restaurant to celebrate for several reasons. The first reason is that it makes any celebration seem more special. The second reason is that the restaurant will have more room to accommodate a large group in comfort and will enable a family or a group to concentrate only on the celebration without someone having to work for hours in the kitchen. At the end of the celebration there will be no clearing up and no washing up.