The Ruby developer couldn't name a problem with payroll that his company was solving; he thought they were just solving a problem called payroll. He was only on payroll for the first time in his life, and needless to say had never himself run into payroll problems. But he was working for a startup with YC credentials that had leveraged new technologies and raised a lot of money, so he could reasonably feel now that he hadn't just joined a company that did something incremental—fixed the various problems with payroll, of which there are many—but something revolutionary, i.e., fixing the problem of payroll.