That is not realistic. Some of the individuals may have queued for it directly to try and clear it for a quest or other reason, and not need another dungeon. Some individuals may have come from a specific dungeon roulette and want to do other roulettes. Some individuals may have queued via mentor roulette and that may be the only one they want to do (and it's a solo queue). Some individuals may be below level 50 and only have access to 1-2 roulettes.

What you can do is type /contactlist to find out which world they were on, world visit to their server and /tell them. Or you can directly add them to your friends list and /tell them. This way, you can form a party with them and become friends.