I think it is funny that the author suggests programmers should use their hobby time to work on something actually meaningful. I feel like he discounted billing systems and ecommerce in the process.

I have no problem with programmers working on other meaningful things during their spare time if they choose. But what I struggle with is why programmers don't work on meaningful projects during their time they dedicate to their actual employment. I feel like I work on something very meaningful because I have helped literately millions of people lose literally millions of pounds of weight. More over, I think Square (a billing system) has helped thousands (millions?) of merchants gain access to a new form payments for their goods that they didn't have before. And Amazon (an ecommerce store) has brought convenience to millions of consumers seeking fair prices for products they want; not mention a new distribution channel for authors and merchants. Those seem meaningful to me.