It would be interesting to know whether TCAS was in use by either aircraft. I am a big fan, because I would not be sitting here if it wasnt for that little box of tricks (I would be splatted on the front of a crab fast jet which never knew I was there).
Yes, you still need to visuallly acquire the other aircraft with a TA, but at least you know your relative altitudes (assuming both are squawking mode C). That gives you some idea of where to look, and the urgency to move out of the way.