Rockin' out, within reason

How do rock stations draw more listeners, mainly older ones, into the tent?  The strategy used to be promoting "classic rock without the hard rock."  In other words, if you're looking for Eric Clapton, The Eagles, and Genesis, the station will have you covered.  It's best to look elsewhere, however, if you want to hear intense metal from someone shouting, "Demon and beast and beast and demon!"