Actually, most people do email and web browsing. There are countless old people using computers to only do that. Linux is perfect for them.
Although I actually agree with you, I expect that Linux's market penetration within that particular demographic is remarkably low. I know a lot of old people who struggle with Windows and Microsoft Windows or Outlook. Too complicated. I fully recognize that Linux would be no worse and may actually be better -- but convincing some old folks may be challenging.
Actually, they're better off with a Chromebook--a laptop that runs on Linux but its interface doesn't require you (mostly) to access the Linux kernel at the lowest level with command-line operations.