Not to turn this thread political, but there are plenty who'd disagree with you on this -or at least the particular wording you've used. Limbaugh was a showman, plain and simple - and rather than "appealing to the values of his core listeners" as you've stated, many would use words like "exploited". No one can deny Rush's popularity and ratings, and no one can deny the "shot in the arm" he gave to the AM band at the time. That said, he also spewed a lot of untruths, hatred and vitriol, made a lot of outright false claims or in the best of times exaggerations. Again, he was a showman and he knew how to stir up his base. There are plenty of stories out there, including books, chronicling people who'd had close friends and relatives that were political moderates, but once they'd been exposed to Limbaugh's program for a time (in some cases because they had long commutes or drove a lot for work and his program was the only spoken word they found to listen to), they'd become almost radicalized, and their trust and belief in his words was almost cult-like.No, Rush made his career by appealing to the values of his core listeners. He also was “at the right place at the right time.” since he appeared around the time of the demise of music on AM.
Problem is, while some saw through his shtick and his on-air antics, many others didn't. As discussed elsewhere on RadioDiscussions, Rush Limbaugh the person wasn't nearly as conservative and far right as his on-air persona. He was an entertainer - But many didn't see through or understand that, and it put the republican party on-course to what it's become today, and it spun off a bunch of other talk hosts who did actually believe in the stuff they were spewing forth, and aimed to be "more Rush than Rush".