Perhaps someone from 2000 years ago, looking at our society today, might have thought that we had a hive mind (at a first glance). After all, you seem to know your friends' birthdays as they know them. You seem to know their messages to you as they know them.
But our society is still stuck in the "ownership" phase. We have concepts of "corporations" and notions like "privacy" and "secrets", which are in direct contradiction to a pure hive state. Even if we have the technology to do it, we will remain bounded and unable to converge into a hive state. The notion that other societies may be capable of utilizing matter to such an extent doesn't surprise me.