To be fair there are outliers in the UK too. The Doctor Who series has been going on since 1968 with 861 episodes too. It’s probably worth ignoring the outliers here and focusing on the median show.
In the UK, Doctor Who is clearly an outlier. The other really long-running shows are soap operas like Eastenders or comedy panel shows.
But in the US, there seem to be an awful lot of outliers, and it's on the strength of those series that Netflix initially established their following: Friends, The Office, Park and Rec, Seinfeld, Community, The Walking Dead, The Blacklist, Gilmore Girls, Grey's Anatomy, West Wing, That 70's Show, Supernatural, Criminal Minds, and I could keep going, honestly, for quite a while.
So yes, there's an extent to which 5 or 8 seasons is less common, but the goal for US shows has been 100 episodes for decades now, which is usually 5 seasons of 20+ episodes each.
If Netflix is adopting a more UK-like approach, that might result in better TV eventually, but it would be nice for creators to know they have to tell their story in 16 episodes rather than 100.
