Where do PhD students get their BA from?

My guess is yes. I think there’s a selection effect - where students who are more predisposed to want a PhD later are more likely to choose schools like Carleton, Mudd, Reed, Grinnell, Whitman, etc. In addition, some colleges simply have a more pre-professional culture, or they’re in a location or have connections that would encourage professional careers or schools (like med, law, business) instead of doctoral degrees. Columbia is one example I am more familiar with; the culture there is definitely more geared towards work right after college (like consulting, investment banking, or finance) or professional schools (like med or law school, or work + MBA) than doctoral degree programs.

This is not a bad thing; not everyone needs a PhD. Nor, however, does it mean that a student who chooses Columbia and wants a PhD is less likely to get into a program than if they went to, say, Swarthmore or Grinnell. It’s true that they may get swayed by the culture - aka, they intended to be a professor as a freshman, but due to the influence of their peers and the connections and resources available at Columbia they decided to go into investment banking instead. It’s also true that Columbia is a research powerhouse with tons and tons of opportunities for a student interested in doctoral degree programs, so a student with a strong pre-existing interest can easily find the kinds of opportunities they need to get into a top doctoral program.

That’s why I personally would encourage using these lists with a whole shaker of salt…I don’t think they are good ways to choose an undergrad college, not alone, anyway - or even with any kind of priority. A student who really, really wants a PhD but also really wants to go to Dartmouth or Berkeley would still be really well served, as that’s one of the top research universities in the world.