It has everything to do with marketing.
Not one national story mentioned he had surpassed Jerry Rice until 10 months later when Jerry Rice passed him back up.
Brian didn't announce his retirement with fanfare, he quietly bowed out.
At the Awards Banquet Scott Brazda announced the new Brian Mitchell Award and declared Brian #2 all-time. He was actually #1 at the time. I corrected Scott afterwards and he said he was just reading what they put in front of him.
That is the norm. If you don't have a marketing arm, the sports world doesn't remember what they never knew.
I can guarantee you this, if Brian had stayed and retired as a Redskin, he would be in the Hall of Fame right now.
Fanfare, awareness marketing excitement. FAME