You are misunderstanding. She has high effective dps in Goats. Doesn’t mean she’s the damage dealer in the comp Arguably that’s Zen and Zarya.
Zen has the debuff which is vital to take down targets, its especially good on tanks. Bridg and Rein are able to damage through shields. Rein’s melee and Fireshot allow him to get ult charge. Bridge as well is allowed to get ult charge. Her shield is also good for mitigating damage and protecting her and teammates from tank ults which are very powerful.
High effective dps is she’s able to damage a Rein shield… vs a Junkrat who has to go through 2k shield, D.Va DM, Zarya bubbles (All rotating cds) wheras Bridge bypasses that 2k shield and DM. Ingame junkrat does not get damage done recorded to blockable objects so even ingame Bridgette would have higher damage.