I did this once by accident (bad scripting, managed to abort it,) it wasn’t too bad until sudo told me that the sudoers file had the wrong owner. I then learnt that there are other ways to become root.
OS ran for another ~6months after I re chowned etc to root.
Prior to cloud flare and Google doing DNS, a common one was 4.2.2.2 which is a level 3 IP.