So you finished the Time Temple quests...

Consider this:

http://www.youtube.com/watch?v=3kt8mBKQRlU&fmt=22

They took down Zakum in 108 seconds. Zakum has 482.1m HP.

That equates to: 482.1m HP / 108 seconds = 4.44m HP/second

You must take down all of Pink Bean in 1 hour. Pink Bean and his minions have 7.65b HP.

That equates to: 7650m HP / 3600 seconds = 2.125m HP/second

Sounds plausible to me?

450mil*5 = 2.25bil hp to which melee cannot contribute whatsoever

600mil hp to which melee can only jump-attack

2.1bil hp during which damage is cut in more than half for the most part

Not to mention annoying status effects like stun, seal, and darkness that come packaged with the attacks, the extreme rarity of naricain demon elixirs, the fact that dark knights are pretty much necessary, the necessity of summon control during the fight against pink bean(insta-weapon cancel), and the fact that pink bean will be throwing up 8k-12k damage damage reflect buffs every minute after a certain part of its hp is gone.