It makes sense. Being in close proximity and constant contact helps with becoming friends. I have cultivated many friendships with people I've met with work and it's made my life so much better.

Too small right now to have ERGs that don't apply to large groups but the soccer team, the basketball team, our running group, and those who cycle tend to form friendships that Grease the wheels of interaction at work, apart from it just being nice to have friends.