Wait, GP is talking just about the first few weeks of college right?
If so, I can see some truth to this. I can't think of anytime in your life you'll ever again not only have no commitments, but also be surrounded by so many people who haven't yet formed (social) relationships. Makes sense to 100% focus on meeting people and building friendships -- it only gets harder going forward.
Of course being in a relationship and having other friends are not incompatible, but the time commitment, reordering of priorities, strain on your mental/physical/pecuniary resources will almost inevitably harm your relationships with other friends.
Not to mention being in a relationship with someone can lead to profound changes in a person's character, and those changes may not gel with existing friends...
You seem to be suggesting the two are incompatible, but in my experience that's not really the case at all...