Seinfeld was a sitcom about... nothing? Not really. It was actually about how a comedian gets his material. But by design, the characters never really developed or changed. They did not care about each other unless their own interests were seen-to, first.
Yet this series is the source for so many gags and even tropes found in many other sitcoms that came after it. Friends copied dozens of bits from Seinfeld. But Friends' characters cared about each other and were capable of growth. Seinfeld's main characters are definitely friends, but they are very much not Friends.