If you think buying ads is the only form of marketing, sure but advertising is probably 10% of marketing. See my other comments to see why he was a natural marketer and used some key tactics that he specifically chose for promoting himself.

I respect the hell out of Bill Hicks but the dude absolutely sat around thinking about marketing and getting his name out there. You have to if you want to be a working comic. Hell it’s not like he didn’t have an agent.