I think soap opera might still be correct.
As you watch a Soap Opera it becomes apparent that all the drama has no real consequence, and thus becomes meaningless. That is why General Hospital can be on for 40 years or something at this point. You can watch for a year, skip a year, then come back. You missed a ton of events, but it doesn't effect what you take from the show.
Once "the ending" becomes detached from the show, it is very difficult to manufacture meaningful drama.
Some shows, like Seinfeld or Simpsons always return to a set point at the end of an episode. So they don't need a real ending. This is different than the soap opera. Because there is no illusion of an ending. You know the show isn't going anywhere and you experience just what it is in that moment.
The soap opera is diabolical. As each episode ends, you are hooked, waiting for the next so you can find out "what happens", but there is no ultimate payoff. Just a never ending sequence of false promises.
Soap operas are the worst offenders, who best illustrate the point. But any drama series without a fixed end point is guilty of the same crime. Take LOST, which began as a brilliant show, but as it was stretched out began to anger many people. When would it have become a full Soap Opera? 10 more seasons? My point is that it already was, just shorter than some others.