NBC offered to extend 'The Office' for two more seasons, according to a new book by Jenna Fischer and Angela Kinsey, but the cast thought it would 'ruin' the show to go beyond season 9.
Part of the reason Season 9 is so disliked is due to how out of character everyone is written. Jim would literally never do anything like this prior to S9. : r/DunderMifflin
The Office, Cast, Steve Carell, Mockumentary, & Facts
Look Back at Rashida Jones' Character Karen on The Office
Why Did The Office End? - Cast & Crew Comment
The Office: 5 Things Season 9 Actually Gets Right (& 5 It Doesn't)
Why The Office cast chose to end show at season 9
The Office, Cast, Steve Carell, Mockumentary, & Facts
The Office Ending Explained: Where Your Fave Characters Ended Up
Why The Office Ended After Season 9 (Was It Cancelled?)