This is only true for modern TV formats that favor season+ long story arcs so much that any individual episode often contains neither the start nor end of any particular plot and is entirely meaningless outside of its larger contextual role in the series.
In old-fashioned TV, each episode pretty much had to stand on its own as a story and stood a much better chance of hooking new viewers. The downside of that approach of course is that status-quo is God and almost nothing truly interesting ever happens because of it.
The best shows, in my opinion, manage to mix these in a way such that any individual episode can be interesting even to someone who has never seen the show before, while still creating a larger more interesting narrative over time. My personal gold standard for this is Stargate SG-1, which lasted 10 seasons and started with human beings walking through a wormhole to encounter the monster-of-the-week and ended with them zooming across the galaxy in starships and fighting ascended would-be-deities.