Sure, The Coasters were a vehicle for Lieber and Stoller's songs, but they were a great vehicle .For so many Lieber and Stoller songs they were the only one .All you have to do is listen to some of the cover versions .Even Elvis made a complete hames of "Little Egypt" .And I agree that the Doo-Wop style of singing came from the Black community ,but many of the songs came straight from the mainstream, white, pop music of a slightly earlier period, originnally written in a "white style".
Jerry, I have Gillett's book ,somewhere in one of my shelves ,I must dig it out and read it again. From what I remember it is a wealth of information .