There were way too many legendary summoners playing today's quest I lost count of the number of Yodin Zakus and Llamas along the way. Kind of insane when you think about it that they are all playing in Bronze I with one reward card after completing the daily quest.
I'm not sure it is worth it given that they are losing out one 2-3 treasure chests per day by not playing in the Silver league.
Having said that, maybe getting 15 additional DEC is hardly worth it.