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.
Anyone with firsthand access to NFL, MLB, Premier League Soccer(and other pro sports) financial info will attest to the lack of book earnings. see for eg
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.