Regarding #5, the main reason why these substances are banned is that they have long-term health consequences beyond what normal performance in the sport might do to the athletes. It's not just a matter of "ok maybe we just have separate clean and doped leagues so we can have literal supermen running around the sportsball field".

That being said, the NFL already chews through athletes anyway so maybe they've already silently decided "football[0] is just inherently doped now".

[0] American football