"They" have. Gentoo or Arch may not provide you with a GUI, but Ubuntu, Fedora, Mint, etc does. You can do everything from installation to disk formatting to network and firewall configuration to office work to video editing to programming all without ever touching the terminal.
When you've only ever used Windows, every problem looks like it needs a GUI. But in the real world, many problems are much easier solved with a CLI. This isn't an either-or, it's different tools for different jobs. Do you think Microsoft implemented an Ubuntu subsystem for the lolz?