> It wouldn't matter; you'd still be free to sell it as an unregulated supplement.

Patent protections on supplements are very weak compared to the protections afforded to FDA approved drugs.

That alone limits research into supplements.

Also what counts as a supplement is limited, companies cannot just declare any random drug to be a supplement. Dietary supplements have to have some tenuous connection to being from a natural source. (Though obviously that line gets skirted a lot, such was with DMAA prior to 2013)