I don't know, there seem to be a lot of exceptionally knowledgeable layman on this forum, but those of us common folk, who study our religion from non-primary texts, typically learn something from sermons. I can't say I've ever heard a sermon that misstated anything theologically speaking, to my knowledge. The laity learn from sermons. At 56 years old, there's only one priest I've heard who gave a boring, real boring, sermon. He was young and ended up being disfunctional, and was later unfrocked. Others vary in terms of how much of the sermon kept my attention, but overall, sermons are most helpful to the overwhelming majority of the common flock, and their effect shouldn't be minimized. Most of the people do not study the Faith in any way; many do not pay attention to the hymnology. Sermons are instructional mechanisms that enlighten.