Because the right to determine distribution channels and the right to prevent distribution are inseparable. I challenge you to write a law that successfully implements one but not the other. Any law you write that guarantees a creator control over who distributes their work and how will inherently allow that creator to literally or functionally prevent distribution.
The alternative is saying that creators don’t have a right to control distribution at all - anyone must be allowed to reproduce and distribute, even if not for free - and that is a known disincentive to invention and economic growth; there’s a reason we only enforce that requirement in select places like standards and protocols