This seems like a safe assumption? I guess you can marry a couple coworkers in the course of a career but how else are they going to become family?
I don't see that as antagonistic. Work isn't your family. The purpose and circumstances are entirely different. It doesn't mean throw all your coworkers under a bus but the relationship is fundamentally different.
Still, I don’t think “work is not your family” is antagonistic and I don’t think it implies you can’t form meaningful relationships with your coworkers. I interpret it from the other direction more like “don’t expect your coworkers to be your family”.
On one level there's my "real", immediate family (my spouse, my children). On another level there's my "real" extended family (parents, other blood relatives). On yet another level there's my "adopted" family (close friends, their children, etc.)
It's pretty easy to see certain coworkers moving into the adopted family category.
I dunno, mine certainly does. My family extends only to where they're no longer toxic in my life. When they intrude and become a negative influence, I cut them out.
My gripe with the antagonistic "work is not your family" approach is it sends the signal that the people I meet at work will never be my family. That kind of sucks. Sure, corporations cutting people out aren't very familial, but there are other humans at the core and some of those coworkers do care if I get fired or am having personal issues. Unilaterally casting them out as a machine to further my personal interests is throwing the baby out with the bathwater.