The whole question of whether top colleges choose the brightest and best is presented as if it is wrong for colleges to choose bright students. I have a problem with the whole idea that it is wrong for colleges (top or otherwise) to select their students. The whole point of college is to educate and the best and brightest students are the ones that are more likely to benefit from this process. If a student does not have the ability that is required on a course then they should not be allowed to take that course and if they are allowed it is just setting them up to fail. If colleges admitted any student just because they were capable of filling in the form for admittance, but were not capable of actually learning the material that the course required, colleges would be accused of simply taking the money without regard to students welfare.
The students who are at college for the education are usually the ones who will gain good results and go on to work with a good attitude. This usually means that they work hard to pass exams and to do that needs dedication and commitment, both are qualities that are usually found in the best and brightest students. Some people are very bright but do not have the dedication and commitment that is needed and would find the work hard because ultimately that is not what they want to do, they therefore should not go to college at all. These are the people who will party instead of completing assignments and if they were in a place of work would be told to either buckle down and work or face the push. Colleges do not do this and so the people that are most likely to party are the ones that the good colleges are likely to filter out.
College is usually taken at a time in life when it is important for the individual to socialise and spread their wings. This is an important part of the development of each person and college is an ideal place for this socialisation process. However, socialising can be done while still studying and this is where the brightest and best come into their own. They prioritise what needs to be done and do it and this ensures success for them and good results for the college. This is what makes the college a top one.
If the top colleges were not allowed to filter out the slackers and had to take them, the brightest and best students may be put off academic life as the emphasis would change from academic success to that of party and social success. This would create a slide from which there would be no return and the education of the country would decline.