Words literally change their meaning over time and social context.
I think "guy" used to mean just "a rope" until some fellow named Guy tried to blow up some nobs in London.
I think both "guy (rope/guideline)" and the name "Guy (Guido)" might origiate from the same basic word "guide" .
I don't think it's always clear why changes happen, people just use it differently and if a new usage spreads widely and becomes common, then the new usage may get added into some dictionaries.
I quite like "RobWords" on youtube - 'tho I'm not sure if he has covered this one specficaly.
sudo mkdir /dev/heaven
sudo mkdir /dev/earth
sudo chmod o+rx /dev/earth
sudo systemctl start light.service
(/s, just trying to troll some systemd haters)