Everything is streamed live now, so it's a thing of the past to say anything is being held until later. It's not as if all these networks are showing reruns of entertainment programming as opposed to the Olympics. NBC has made a lot of decisions over the years that aren't exactly viewer-friendly, but thankfully they've evolved out of it. But they still have an unfair reputation on some times because people don't realize it's not the same NBC coverage we got 20 years ago.
The theory has always been "you wouldn't tape delay a football game, would you?" Of course they don't, people wouldn't watch that. Different with the Olympics which is largely a collection of shorter events. It's not a 2 hour basketball game or a 3 hour football game. People will come to watch as long as the video is first run. Especially if Americans and popular athletes are winning. That's why NBC will tend to go all in on certain athletes (not that other countries don't have their favorites, but they're more reliant on the world feed which is supposed to remain netural.
The other business aspect of television in the United States is that broadcast networks are not allowed to own the majority of the stations that broadcast their signals. So they need to keep their affiliates happy in ways that other countries and their broadcasters don't have to deal with. In 2002, Ebersol wanted to broadcast the primetime show live to the West coast. The affiliates pushed back. For them, it was better for business to have a delay. That's why it stayed like that for a long time until 2018 when the West Coast finally got the same primetime show. And that's largely because it's an Olympics in Asia with live events in West Coast primetime. Same here and for Beijing as well.