Because a GUI makes everything a lot simpler.
I only started understanding how git works the moment I dropped the GUI and had to resolves issues through CLI.
Yeah, some companies are very slow to adapt. One company I worked for was still using SVN. It was a nightmare lol, and when they did finally migrate to git, some of my coworkers were completely lost.
But there's also something to be said among developers I've worked with on hobbyist projects. Plenty of people who just shared files over and over, or just had it on Google drive or Dropbox
We hired a guy 2 years ago and his company was still using MS Virtual SourceSafe. Dudes, that was released in 1994 and the last update was 2005. Just crazy.