Basically, tv drama was largely hit and miss for most of its existence. There are some outliers but basically they weren't seen as on par with cinema. In the early 2000s you got several tv shows through HBO such as the Wire, The Sopranos and Six Feet Under that basically changed the standard of what TV drama could be. Shorter season durations, more nuanced writing, more profanity and themes not usually considered suitable for the prime time slot. Part of was that HDTV was also making the viewing experience at home more enjoyable. Mainstream cinema also kind of sucked in this period.

From that you get your breaking bad, mad men, Friday night lights and in this generation it's Succession The Handmaid's take, ozark, Barry, Better Call Saul etc.

In short, tv drama used to be the super poor cousin to feature length films but now it stands probably in equal stature because of the prestige television movement