The point of the ruby script is to set up paths and before launching the actual emacs binary, since starting a gui app under macOS doesn't do most of the things that a unix-based application like emacs probably expects. (To be fair, there's only about 60 years of precedent built up, so...)
The other side of the coin is this: macOS uses an ever-tightening security system that is intended to prevent users from unintentionally running "dangerous" processes. I stopped using macOS before the current generation of these systems, but they do fairly typical security-system things, including restricting access to parts of the file system and refusing to run/hampering unsigned/untrusted binaries. There is a way to tell the system "yes, I know emacs isn't security-blessed; run it anyway" -- that's (I presume) what that xattr command does. Wrapper scripts present a new problem: are you security-blessing emacs, the wrapper script, or both? Just saying "yeah, any ruby script can run whatever it wants" is probably not the sort of operation that the OS security team wants to make trivial.
As an alternative to the wrapper-script approach, there used to be an emacs package that helped with some of these issues. IIRC, it's currently called exec-path-from-shell.
Hope that helps,
~Chad