No BS can prevent any student from applying to any particular college but, because the GCs are intimately familiar with the applicant pool from their school as well as the typical number of offers from each university each year (no hard quotas but general ranges that persist year after year), they will cull the herd by:
- Encouraging and supporting the strongest, most competitive applicants
- Suggesting alternate schools that are similar in the areas important to less competitive applicants
- Discouraging applicants who don’t have a snowball’s chance* from wasting an application
I’ve posted ChoatieKid’s experience many times over the years, but it was similar to @buuzn03’s. After Army and Navy, ChoatieKid was interested in strong engineering programs, and he was stat-competitive for any of them. His GC told him he didn’t have a shot at the three or four offers that would come from MIT because she knew his competition, but CMU, Michigan, UIUC, and Georgia Tech were all reasonably in his wheelhouse and she would fully advocate for him at each. If he wanted to apply to MIT, he could, but he would not get the same support, so the application would be a waste.
From the BS point of view, it is not in their interest to encourage useless applications that would dilute the credibility their college relationships are built upon. Proper gating is very much what colleges expect from the boarding schools and, to that end, the back-and-forth between them is designed to let the boarding schools know what they are looking for in any particular year and approximately how many offers they have for that school’s bucket. It’s then up to the BS to advocate for those best matches. There’s no horse trading, but it’s a highly curated process, especially with the most highly-desired colleges.
*At BS, not having a snowball’s chance is more due to the strength of the senior BS pool than any glaring weakness in a particular student. A high percentage of most BS classes is Ivy qualified but, among those both qualified and interested in applying to those schools, there are not enough seats to accommodate. GCs should be very frank with each applicant about what their chances are, set expectations accordingly, and help each hone a list primed to achieve the best results for that particular student. I have not heard of pre-determined lists, though. What would be the point of that?