Did you ever write a single line of code in your life? What about open source lines of codes? Do you know I wrote millions of open-sourced lines of codes? (including stuff you probably use daily)

Obviously forking a repo and forking a blockchain are two different things (it's always possible to re-merge the forks together in the case of code). There is no philosophical reason to why it's possible to fork. That's just the way it is.