Grandma likely isn't able to use most existing web apps beyond facebook, her default email client and little else either.

Uncle Bob on the other hand will stop nagging you to make him those apps you never have the time to make him and will do it himself. He is a handyman, literate and numerate and able to use a computer like most middle age folks outside of tech can. Uncle Bob's mates at the local bar will see the software he wrote and will get into it themselves.

The Gen X+ non-techie population is made up of more than just grandmas.