Claiming that the NBA one-and-done rule is racist because the "white sports" of baseball and hockey allow players to come straight out of high school into their minor league systems is completely idiotic, since the NBA already allows the same. The one-and-done rule doesn't allow 18-year-olds to be drafted, but they can enter the G-League and play for pay if they want.
And they can hire agents all they want, they just can't do so and utilize the personal exposure and marketing that the NCAA provides. If the on-and-doner's weren't realizing some benefit from engaging with the NCAA system, they wouldn't do so; they would use the other more lucrative avenues available to them. The fact that the Terrence Ferguson's and Emanuel Mudiay's of the world are so few and far between is pretty clear evidence that the kids who do choose to go to college for the one year receive a lot more from playing at the NCAA level than the critics are willing to admit.