Some more input on mob leashing:
https://forums.daybreakgames.com/eq/.../#post-3506837
"Long ago Kunark mobs did this while mobs in vanilla zones did not. It was possible to hold a long range bow and hit monsters outside of aggro range in Kunark. At some point I think it became the standard but I'd have to check again. Not aware of specific changes made."
Looks like everyone / most people agree on the fact that vanilla zones should not have leashing, Kunark zones should, and Velious - unsure.