This wasn’t my experience at all, perhaps largely because Duke has changed quite a bit over recent decades. Duke has gone to great strides to foster a more inclusive and intellectual environment on campus in the last couple of decades – offering funding for students to take professors to lunch (FLUNCH), for example, and implementing a house system on West campus.
FWIW, I was an independent and a humanities major (and science double major) who chose Duke after my top choice (Chicago) offered woefully inadequate financial aid. I found a great group of quirky, nerdy friends, took stimulating classes, nearly all of which had <20 students, and was very well prepared for getting my PhD afterwards. On a more personal note, I’ll add that I came out while I was at Duke and found it a wonderfully accepting and supportive environment. It seems bizarre to me to say that Duke isn’t a good fit for anyone looking for “intellectual and personal self-discovery.” There’s students of all stripes on campus.
I won’t dispute that Rice sounds like a great fit for OP - quite possibly a better fit than Duke. (S)he can definitely find those students at Duke too, however.