This isn't as much about what existing extensions do today but all about what potential extension could be doing tomorrow. If an extension doesn't get full acc

This isn't as much about what existing extensions do today but all about what potential extension could be doing tomorrow. If an extension doesn't get full access to all the pages you are reading, it can't do bad things with that access when the extension's owner inevitably changes (see the fight between uBlock and uBlock Origin for example) and spyware features are added.