I think that it's good advice for people with interests outside of tech. If you are a developer, then it's easy to think of things that you could make for other developers, but for various reasons, developers aren't a great commercial market.
There are probably still a lot of non-developers out there using bad software, because developers with a genuine interest in that field and the skills to make great products for them haven't showed up yet. I work for a SaaS company that found a poorly served market, and it's been like pushing on open doors: there were a whole bunch of people with the same problem, but it's not a problem that developers care about, so the most popular solution in the market before us was Excel spreadsheets.
There are probably still a lot of non-developers out there using bad software, because developers with a genuine interest in that field and the skills to make great products for them haven't showed up yet. I work for a SaaS company that found a poorly served market, and it's been like pushing on open doors: there were a whole bunch of people with the same problem, but it's not a problem that developers care about, so the most popular solution in the market before us was Excel spreadsheets.