I'm from Texas, went to UT when it had the 10% rule. It was a problem for kids who went to competitive/affluent schools that were so competitive that one or two Bs would put you out of the running. So you would get some lopsided scenarios where some kids would get into MIT but also be rejected from Texas because the standards were that high. Meanwhile the valedictorian of a bad school with a 900 SAT score would get in. Some kids would move to less competitive high schools to have a chance at going to UT.