People say that about food, music/dancing, and stories because they are the least antagonistic thing they could bring up while boasting about their culture. Its the least likely to get attacked as well, its a non-controversial aspect they can sing the praises of and its something easily shared

If they bring up their cultural religion, values, politics, philosophy, or social dynamics, suddenly things can become an area of controversy and even ethical debate. Most people are too fragile or cowardly to investigate that stuff.