I think the market prerequisites are a key point overlooked by the article. There has to be some application where a low-performing version of the invention is already useful for it to be worth it to develop better-performing ones. For example, in the case of Watt's steam engine, versions were already used for the application of pumping water out of mines [1]. This application made it economically worthwhile for Watt to work on his improved steam engine. Of course, once the improved version was available, it found many new applications beyond the original one.