Seinfeld is unique when it comes to sitcoms.  This stems from the writing of the show.  Seinfeld was created by Larry David and Jerry Seinfeld.  While Jerry is the star of the show, make no mistake, Larry David is the genius behind the show's success.  When David and Seinfeld created the show, writing was governed by a important rule, which was posted above their writing area:  "NO HUGGING, NO LESSONS LEARNED".  This singular rule set them apart from every sitcom made before, and from every new one launched since.  The show was supposed to be funny, not about relationships and learning lessons.  Jerry would break-up with a different girl in almost every episode, and he wouldn't care, and he would learn anything from it.  Even death was funny on Seinfeld.  Susan dying from licking the cheap wedding invitations that George picked out.  Not only that, but when George hears the news, his reaction is one of "restrained jubilation"!  And we laughed!  We never feel sorry for the characters, we never care about their love lives, we just laugh.  This approach to writing the show was bold and different, and is the basis for Seinfeld's success.  And no other show has tried this approach since, and I wonder why.