Instead of "files", they should have called it "objects".
Unix is an object-oriented OS.
(The nomenclature is quite backwards. It would be like building a database of employees, companies, etc. then saying "everything is an employee", companies are just a special kind of employees.)
The problem with "everything is an object" it doesn't tell you a great deal off the bat. It's like saying "everything is a thing". Sure, it's true but it's not helpful.
In your "companies are just a special kind of employee" example well if that is true within your data model then that is quite interesting and contributes to the listeners understanding of how things work. The alternative "companies are a just a special kind of entity" is less useful.
Unix is an object-oriented OS.
(The nomenclature is quite backwards. It would be like building a database of employees, companies, etc. then saying "everything is an employee", companies are just a special kind of employees.)