You're missing the point of what he's saying. Currently a mch/brd can literally 100 - 0 someone in a stun. That kind of burst shouldn't be happening period. It doesn't make for good game play to suddenly vanish from one source of damage. Throw in melee and warrior focus fire and the damage is unhealable with minimal coordination.
The problem with SMN damage in pvp isn't cause painflare/deathflare don't hit as hard, it's that the bulk of summoner burst is tied to 2 conditions, having full dots on a target and having 3 stacks of aetherflow/trance. Both are painfully obvious and can be countered much more easily than mnk/drg/mch/brd burst.
The SMN toolkit in general requires too many stars to align to be able to output the kind of dmg that other classes do and that's not something that can be easily fixed just by giving a potency buff here or there.