Interesting hypothesis. Makes some sense. Though, you mention soaps. Those are very long story arcs. One of the longest, I recently learned, is "Robin Scorpio" from General Hospital. She started when she was 5 (I think), and is still playing the same character 40 years later.

en.wikipedia.org - Robin Scorpio
OK...she started when she was 7. I don't watch the show, but this says her last appearance was 2021. So she was 43 at her last appearance. But, yes, with the exception of the occasional recurring character, most programs were disconnected episodes (Love Boat, Fantasy Island, Combat, even Star Trek). It was a big deal to have a two-part episode in those days, and I don't recall any cliff-hangers (unlike the Lioness, which we just caught up on, and Jo looks like she's going to be hunted some more by a mysterious adversary next season).

Though even movies weren't as good (generally...always exceptions like The Godfather and The Sting). Compare any John Wayne war movie to anything from the past 30 years. Wayne gets stomped in terms of quality of story (and acting, but Wayne was not a good actor...he played himself in every movie).

I also think it's the studio execs. Two examples I can think of were Babylon 5 and Firefly. Both creators were messed with during production by studio execs**. They wanted bar room brawls and such. A lot of those out-of-touch old men have since died, which may be at least partially responsible for the shift. Which is how we can get a clean The Expanse, aired in order, and a very complex story with lots of moving parts. Perhaps the execs of old were taking the advice "no one ever went broke underestimating the intelligence of people".

Yeah, I remember re-runs. Now "syndication" (so I could watch TOS again, if I wanted), which allowed me to quote whole passages from TOS by the time I was 16. It was how the studios filled the gap between seasons (22 weeks of season, and 30 weeks of break).

**I read that Straszinski had registered the name "Iben Scrood" with the union, and when execs were forcing him to make changes he threatened to use that in the credits. As I understand it, they relented. For Firefly the execs aired episodes out of order, as if there was no story arc.