I would consider the Sports Broadcasting Act and the following legislation that expressly permitted the AFL/NFL merger to be, as you imply, well-known gifts from Congress to American professional sports leagues and the NFL in particular.

Those are hardly loopholes, however, since the legislation worked exactly as Congress intended as far as I can tell.

Your allegations of "Hollywood" accounting seem more consistent with loophole exploitation, but I would like more concrete evidence other than the alleged dearth of team profits.