Well that's also unfair. Joe and Gary started their company from scratch in the late 80's and moved quite a few machines til they split at the end of the 90's, and obviously the company is still going strong today.
Williams had a 40(?) year head start on them, acquired Bally, had all the patents, all the talent, and they couldn't make it through the 90's. Doesn't matter how many machines you sell, if the BOM is high and the machines go into closeout pricing, and every designer is an overpaid diva who gets $250 a machine, then you're a leaky vessel and the end is near. Wms, and the people in charge of pinball, didn't realize this until it was too late. Probably because they were given free reign for so long, with less oversight, compared to what Joe had to work with a large Japanese parent company.
Also worth noting is Williams almost didn't make it through the 80's even! Joe was part of the team at Williams behind Space Shuttle. Williams factory was described as nearly dark when they were working on Space Shuttle, and it was a huge hit that turned the company around.
Keith's point about their lack of engineering is a valid one, as even Joe has stated one of the things that held back DE was not having better mechanical engineers. But given what he accomplished, King of Licensing, King of the Paper Napkin Sketch, etc are all more appropriate titles. I think he artfully squeezed a lot out of the resources he was given at every company he worked for.