Here's another reason:

The Fargo series (and ultimately the movie) thus far was about an event happening, and then watching people make poor decisions around that event.

S1: Lester Nygaard covers up the killing of his wife.

S2: Peggy Blumquist attempts to cover up the hit and run and homicide of Rye Gerhardt.

These events kicked off the rest of the story. All the characters were reacting to these events. Season 4 of Fargo there was no opening event. And like people have mentioned in this post, I loved the setup. That first episode showcasing the history of the gangs in the town was great. But when there wasn't a clear event everyone was reacting to, the show seemed to depart from what made it great. I don't want to call it a formula, but the way they're telling this story isn't unique in any way.