It seems like every "great" piece of software, e.g. the operating systems of Apple and Microsoft, the search engine of Google, AWS inside Amazon, Facebook etc was dogfooded.
I don't think you're wrong. Most of my career has been working on specialty software that no individual (including myself) could use, and therefore can't be dogfooded.
How is facebook dogfooded? Do they buy facebook ads?
And wasn’t windows originally created as a product for sale? I don’t remember microsoft starting as hardware company. Maybe that is why windows sucks :)