At Hillsdale College, which is academically rigorous, I believe it was 30 percent of incoming freshmen several years ago were homeschooled, and the homeschoolers made up (I think) at least 30 percent of the honors program, so they were obviously very solid academically. OD, your assertions are simply too broad that homeschoolers are not "college" material.
Furthermore, homeschooling is not just for the gifted, but also for the struggling student who can work at his or her own pace and not just get a low grade for not "getting" the subject. In our homeschool, if a child caught onto a concept quickly, great -- we moved on. If not, we spent the time on it until the concept was understood.