Hong Kong directors' palace-level lineup, the "band of seven" is not only for nostalgia, but also for what?

Band of Seven is a unique film. From 1950s to the future, each of the seven Hong Kong palace directors drew lots to direct a story of an era, and demanded that a film must be made, and each director directed a short film related to that era in Hong Kong. The name of the movie is band? The finishing touch? It means that directors with their own styles and talents, like excellent musicians, can create wonderful music together.