chroot only makes sense for applications which can commit to exclusively operating out of a single directory, ever. (It also requires the process to have superuser privileges, so it can't be used by applications which are run as users.)

os.Root() is more about putting a "seatbelt" on filesystem operations - like restricting operations related to an application's cache to its cache directory, or restricting a file server to serving files from the appropriate shared directory. It's not the same kind of ironclad guarantee as chroot, but it'll still protect an application from simple directory traversals.