Yeah exactly, PR's are based on the fact that you have some person who is the owner that have complete power, and many other contributors who have zero power and whose contributions will mostly be rejected. You simply don't have that situation in a company, where everyone is an owner on equal terms, and all contributions are accepted, only some with slight modifications.
So you get these really weird situations where more junior, or less skilled, people can block PR's and demand changes from other more skilled and/or senior people. And if there's disagreement in a review: the resolution of that is completely unknown, and can often blow up to a really nasty conflicts.
I have so many terrible experiences with PR's where you get hostile nonconstructive comments on your work, on github, from a person that literally sits next to you. It's the creepiest thing ever.