All classes have DoTs, and all classes have ramp up time.

Also summoner is by far the best dps on boss when you don't have 100% uptime on boss.

DoTs tick regardless of whether you're on the boss or not, and summoner DoTs are ~60.83 pps, which is roughly 65% of a summoner's personal dps, or 75% of the summoner's total dps (including pet on boss) even when the summoner is doing nothing but staring at the ground.