The most obvious is that people need to make a living I think this is why YC and other incubators exist today to help developers financially so that they can w

The most obvious is that people need to make a living I think this is why YC and other incubators exist today to help developers financially so that they can work on Real World Problems rather than coming up with another photo sharing apps? I also wonder why YC did not encourage devs who want to work in such domains. Aza Raskin's Massive Health is the one which comes in my mind that is doing something for humanity.