@hassan it's in the middle of the article:
"It’s actually written in the N.F.L. bylaws that no team can be a non-profit, community owned entity. The late N.F.L. commissioner Pete Rozelle had it written into the league’s constitution in 1960. Article V, Section 4—otherwise known as the Green Bay Rule—states that 'charitable organizations and/or corporations not organized for profit and not now a member of the league may not hold membership in the National Football League.'"