Both guys were stand-up comedians (I don't think either was/is good). Both guys had a show on NBC (Fear Factor/Who Do You Trust), but their popularity is from interviewing others. Back in the day, if Johnny Carson liked you, and invited you back on the couch after you did your set, you were on your way to greater opportunities, and perhaps a TV sitcom. If you go on Joe Rogan, you're going to get noticed, get a sales bump, and like a spark, you can YouTube everything about a guest you like.
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