What's the Deal With Staff of the Dreaded Gaze?

[Axoc]

Wiki gives it a 30 day average of 35,769 plat. Why? It has unlimited casts of a 7.0 second, 0 mana cost version of Invoke Fear, which normally has a 2.5 second cast, 100 mana cost. I get why that could be an improvement - it's slower, but it's free on mana, and if the mob is already feared, it's a free re-Fear. And (probably the most important part) it saves a spell gem, which would be great and all...

Except:
When you're fear kiting, you typically only need 5-6 gems, NOT 8, and certainly not 9.
You have to equip it. It has horrific stats (especially considering it's 2 handed).
By the time you're level 40 and able to use it for the Fear, if you were sitting down, you would have gained more than 100 Mana (ticks being 6 seconds mean you'll lose one Meditate tick by using the staff versus casting Invoke Fear between ticks).
It costs (or opportunity costs) nearly 36,000 plat.

I don't get it. What's the big deal? Why does every Necro seem to want one?