There has been much talk in recent years about the death of the sit-com. Googling that phrase in quotes brings up 8000 entries.
There has been no satisfactory explanation as to why the sitcom has died, though.
However, I think I know the cause.
Cell phones. Cell phones have ruined the sitcom.
Because so many comic situations revolve around missed connections and the like. The ubiquity of cell phones nowadays eliminates a lot of potential comic opportunities.
For example...let's look at Seinfeld.
My favorite Seinfeld episode is probably "The Bubble Boy." If cell phones were ubiquitous in the early 90s, that episode wouldn't exist. At the beginning, George would have called Jerry's cell phone and talked to him, rather than calling his home phone and leaving the answering machine message about Jerry's girlfriend laughing like Elmer Fudd sitting on a juicer. Thus, she would have gone to the cabin with Jerry instead of Elaine.
Then when Jerry was following George to the Bubble Boy's house, if there were cellphones, when Jerry lost George, he would have just called him and they would have been able to reconnoiter. Jerry and Elaine wouldn't have been stuck at the diner. George and Susan wouldn't have been playing Trivial Pursuit alone with the Bubble Boy. Kramer would have called George and Jerry to say that he was coming to the cabin, resulting in them figuring out an excuse for him not to come, thus eliminating the issue of the cigar being left in the cabin. The cabin then wouldn't have burned down.
That carries over into the next episode, when the cabin burning down reveals that Susan's father and John Cheever were lovers, but that's another issue.
But think of other episodes of Seinfeld. "The Parking Garage"...in that episode, they would have split up, each of the four searching a separate area of the garage, and whoever found the car would have called or texted the others when it was discovered. Episode moot.
Same with the episode when they all saw "Rochelle Rochelle" separately, because they couldn't connect at the movie theater. Or the episode where Jami Gertz didn't have a square to spare...Jerry and his g.f. were supposed to meet Elaine and her b.f. at the movies, but didn't connect. A cell phone would have ensured they connected, thus making much of the ensuing stuff inapplicable.
There was the episode called "The Keys", dealing with conflict over abusing the Covenant of the Keys. A key part of the episode was Jerry getting George to use his spare keys to Elaine's place to let Jerry in so that Jerry could get his spare keys. Elaine discovers them. If cell phones were around, Jerry would just call Elaine directly so she could get him the keys.
Or the episode where George and Jerry were supposedly gay (not that there's anything wrong with that)...the whole thing starts with Jerry not connecting with the NYU student who is supposed to interview him at Monk's. Nowadays, he would have called her cell, found out she was there, they would have done the interview, and she wouldn't have overheard Elaine and George pretending that Jerry was gay. The whole episode goes away.
The internet and other technological advances also contribute to the elimination of humorous situations in sitcoms -- for example, nowadays, Jerry would have a GPS to direct him to the Bubble Boy's house, or would print out directions with Google Map.
But I think cell phones are the key. Cell phones make it too easy for people to connect immediately. That has eliminated too many humorous situations, and has killed the sitcom.