In a word, regulation. Read here about how our good friends at the Food and Drug Administration now have even greater power to muck about and keep small businesses from competing with big businesses.
Isn't it fantastical that so many people seem to be perfectly happy with the proposition that a bunch of bureaucrats in Washington can and should tell everyone else what they can and can't do in matters economic?
Why does anyone think that some small set of bureaucrats (all of whom are just people, by the way) will have either the information necessary or the incentives to regulate voluntary exchange among consenting adults?
People who favor top-down regulation always have some ax to grind. See if you can understand who is grinding what ax in the new regulatory powers Congress just gave to the FDA.