People don't play smite clerics because smite clerics were nerfed way back in the day. Prior to SI release, smite clerics were all you would see. You would be hard pressed to find "healing" clerics as it were. Most builds were simply 44 Smite, rest into buffs and heal. Whereas in the other realms, people had more of a choice.

In Midgard, Healers had multiple roles to play. They were main CC as well as the main heal class for the realm. In Hibernia, you had buff druids as well as heal druids (pet druids were the overlooked line of that class). People didn't stop playing smite because they couldn't get groups. They stopped playing smite because it wasn't a wizard in chain anymore.