Reducing competition for draft picks, not minor leaguers. Prior to the draft, they could sign with any team. With the draft, they can of course only sign with the team that drafts them. I am too cynical to believe that MLB does anything out of fairness. They've been tinkering with the draft all along closing loopholes and changing signing rules to keep down salaries and bonuses down. Sure, the draft also helps competitive balance to an extent, but keeping down salaries is an important purpose of the draft.