Of course! They come up with a new ruler, and then they come up with a pattern that uses the ruler. Then they give you the pattern for free - creating demand - and oh hey, there's a ruler to help you! $$$ (And if they're REALLY good, they can make you pay for the pattern, too!)
It's the same thing every industry does. It's up to us to decide when it's a worthwhile investment and when it's a gadget that will sit in a drawer.