So I love good old fashioned desktop-oriented websites, and the most complex thing I do on my phone is Google Maps... but I also recognize this is not true of the general population.

Almost no one else except the PC gamers I know really like using desktop (or laptop) computers. Most people love being able to sit on the couch and use apps on their phone. Its not like massive portions of the population were loving their desktops until smartphones arrived and they transitioned, no - smartphones are what helped the internet revolution really inseminate into the general population.