A potential benefit could be a more efficient use of resources. Focusing resources on students demonstrably prepared for rigorous academic work might lead to higher graduation rates and better outcomes for those students. It could also potentially raise the overall academic standards of higher education institutions.
However, there are significant drawbacks. Defining "good" is subjective and could lead to inequitable outcomes. Factors like socioeconomic status, access to quality high school resources, and learning differences are not always reflected in standardized test scores or GPA. Restricting access based on a narrow definition of "good" could perpetuate existing inequalities and limit social mobility. Furthermore, it could discourage students who might thrive in a supportive college environment but don't meet arbitrary high school performance benchmarks. Many students blossom later, and a rigid cutoff could deny them opportunities for growth and personal fulfillment. Finally, a diverse student body enriches the learning experience for everyone, and limiting access would diminish that diversity.
In short, while focusing resources on prepared students might seem efficient, the potential for unfair exclusion and the loss of diverse perspectives outweigh the benefits of such a restrictive approach. A more equitable and effective approach would be to focus on improving access to quality high school education for all students and providing support services to help them succeed in higher education, regardless of their high school performance.