Correct me if I am wrong, almost all the zones have 3 dolmens.
When this being the case why almost all the dolmen farming happens primarily in Alikr and Auridon alone ?
Kalthar Wolf-Brother – EP Templar - 50 Maeli Valen - EP NB - 50Naps-During-Trials – EP Templar - 50Rulnakh - EP Sorc - 50Azrael Krieg - EP NB – 50Uvithasa Telvanni – EP DK – 50More-Tail - EP Warden - 50Narile Galen - EP Sorc - 50Bone Soldier - EP Necro - 50Naps-During-Trails - EP Necro - 50
You do see dolmen farming in other zones, particularly Deshaan and Bangkorai, where there are gear sets that are still in high demand. However, as others have said, Molag Bal attempted to compromise the wayshrine transportation network in Auridon and the Alikr Desert and failed, instead allowing players quick and easy access to his dolmen locations. For experience grinding, Auridon and Alikr are the quickest dolmen rotation. Under the principle that time = money, or at least that time = experience, players prefer to do their grinding in those two zones.
Generally I find dolmen population as related to convenience to wayshrine and the set jewelry available. For example, the dolmen in northern Bangkorai is within sight of a wayshrine and offers popular Spriggan jewelry - there are always folks there to farm it.