yet another migration question

New Contributor

Hi all!
I've read different threads about user migration to a new Active Directory domain and looked at different scripts, as I understood, the main thing is to delete old account with dscl command and provide access to a migrated user account to his folder with chown command.
I've tested migration with Catalina, and it turned out that even without deleting the old account or changing permissions, user still gets to his account and has access to all his files.
I found out that UniqueID is generated based on an AD user GUID attribute, and because, after user account migration this attribute doesn't change, the UniqueID on Mac stays the same.
Could you please explain to me why do we need to do chown command then?
What issues may arise if I don't delete old user account with dscl command?