There used to be less on TV.
It turned off at night. Stopped airing, nothing to see here.
You had three options of what to watch.
Now you have a million.
Population has gone up, and we keep creating. You can't read every book, even if we stopped writing them now, and we haven't stopped writing them! Every day, we add 31 YEARS of new content to Youtube. It can't be done.
So yeah, you get stories of how the ambulances got to Sinatra super fast when he had a heart attack during the Seinfeld finale because everyone was home. Or how toilets backed up after the last episode of M*A*S*H* because everyone waited until the end.
But you don't get that anymore.
The closest you see in the US is with the Superbowl, and even that is dwindling in popularity (source).
Game of Thrones got close, and bungled the ending. But we won't get another mega-series like Harry Potter. There's simply too much to consume.