The benefit of having a single "owner" is in making quick, emergency decisions. That's not really a necessity for an NFL franchise.
That said, the Roonies are very successful, as is Kraft. But imo, alot of that goes to their connections in business politics, etc. Their establishment connections. When Kraft took over that team, it was a major influence in their rise to significance.
The Packers imo, have always been controlled by the Jesuits.
If I'm not mistaken, the Roonies also own or have owned horse racing tracks, which is a violation of the NFL's policy, vis a vis gambling and proximity to organized crime.
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