Can someone give me an in-depth explanation why Summoner is arguably the worst DPS?

[Sanguisio]

I hate BLMs who can do rotations correctly, theres a flippin guide for it xD Btw romsca cast F3 over f1 doesnt yield that much for mana expended and for the most part it will gimp you for MP to Ice stance where you should be reapplying thunder, waiting for that 1tick of mana because you messed and left yourself short.

I know it kinda makes sense to compare SMN and BLM mana as they are both casters but the way BLMs work you can't. MP cost vary and not to mention are higher than SMNs, and their MP regen comes from a mechanic. Also, they are the only class in the entire game that can do their job forever without having to stop.

Now the fact SMNs run out of MP isnt ideal at all and that should be improved upon with to bring it into line or just below MNKs, DRGs in terms of lasting taking the optimal single target rotation into account.

Lets not bring up the BLM vs SMN utility it's been beaten to death, both offer excellent things.