I actually don’t see this is a negative thing, and prefer it sometimes so long as the expectations are mutual. If me and another person are on the same page about only being in touch when the other needs something, and it goes both ways, why waste time trying to facilitate a friendship for the sake of it? Often I find those “friendships” lack substance and just serve to fulfill a social norm that it’s bad to ask for things only when you need them. Perhaps what I’m suggesting is that so long as the social contract is agreed upon (usually implicitly) between parties, there’s nothing wrong with having transactional professional relationships.