You're not exactly the strongest damage dealer out there as a summoner
i'm sorry, what? summoner does indeed put out a lot of damage. It's hard to pinpoint the exact amount because your hate/damage is shared with your pet, and DoT's are currently hard to keep track of using a parser. Why people think it's under powered is because you don't immediatley see their damage. You will notice it in long fights where their DoT's last more than 10 seconds before the mob dies.
I would consider summoner to be one of the better DPS classes even if they did do less damage for just their ability to swiftcast raise, and the fact that they are less likely to pull hate because of split hate between yourself and pet.
From what i hear from other coil groups though, they consider summoner to be better and run with 2-3 of them and say it's faster clearing.
Until their DoT's can be properly taken into consideration and their pet, we will never have an exact definition of which DPS outclasses another.