The fact that copying doesn't copy seems dangerous. Like what if I wanted to copy for the purpose of modifying the file while retaining the original. A trivial example of this might be I have a meme template and I want to write text in it while still keeping a blank copy of the template.
There's a place for alias file pointers, but lying to the user and pretending like an alias is a copy is bound to lead to unintended and confusing results
Copy-on-write means that it performs copy only when you make the first change (and only copies part that changes, rest is used from the original file), until then copying is free.
There's a place for alias file pointers, but lying to the user and pretending like an alias is a copy is bound to lead to unintended and confusing results