Pinball has made a mini comeback in Australia because of the importers' willingness to supply product that was basically dead in this country. The target market has been the older crowd who have paid off their mortgages etc and has disposable income to spend. The hobby has always been there, and people like Steve Young and Clay's Guides made sure it was easy to learn and maintain home machines.
There has never been marketing in Pinball. The only marketing was from Pinball Companies to operators. The machines on location WERE the only form of marketing. Remember, pinball was produced as a method of maintaining an income. There may have been mini ads on TV in the 90's, bet nothing before.
The difference between Pinball and other hobby / luxury items is the simple fact they are made to make money. A car, Jet Ski, Hi Fi System etc etc is not going to make anyone any money. Pinball is an "odd" hobby that levers off the glory days when pinball was king. It is easily the most expensive hobby.
The internet has certainly helped, and the free advice on forums etc has opened up the hobby to many new people.