Please answer a question about the following article about Affirmative action in the United States:

Some commentators have defined reverse discrimination as a policy or practice in which members of a majority are discriminated against in favor of a historically disadvantaged group or minority.[non-primary source needed] Many argue that reverse discrimination results from affirmative action policies and that these policies are just another form of discrimination no different from examples in the past. People like Ward Connerly assert that affirmative action requires the very discrimination it is seeking to eliminate. According to these opponents, this contradiction might make affirmative action counter-productive. One argument for reverse discrimination is the idea that affirmative action encourages mediocrity and incompetence. Job positions would not be offered to the applicants who are the most qualified, but to applicants with a special trait such as a certain race, ethnicity, or gender. For example, opponents say affirmative action causes unprepared applicants to be accepted in highly demanding educational institutions or jobs which result in eventual failure (see, for example, Richard Sander's study of affirmative action in Law School, bar exam and eventual performance at law firms). Other opponents say that affirmative action lowers the bar and so denies those who strive for excellence on their own merit and the sense of real achievement. Opponents of affirmative action suggest that merit should be the primary factor considered in applying for job positions, college, graduate school, etc.

An argument against affirmative action is that it encourages what?
mediocrity and incompetence