It’s also because like all encounters don’t require you to move during damage.

I can think of three other encounters where Well is just “less useful”:

• Crota, because he can destroy the Well.
• The Hydra from Garden/Spire, because you have to move forward somewhat.
• The Boss from Prophecy, because you have to move forward.

Like if they made more encounters like Rhulk where you can’t just stand still and hold RT then Well wouldn’t be as OP.