They absolutely are, and why shouldn't they? The target audience overlaps with the general Broadway audience. Tickets are expensive and people want to be entertained first and foremost when seeing a show. Broadway is a business and it's a big enough tent to allow for Cher and Sondheim to coexist.
Though, few of Sondheim's shows did particularly well, even forty years ago, now did they?
"...everyone finally shut up, and the audience could enjoy the beginning of the Anatevka Pogram in peace."