A rest simply allows for a much more forgiving and easier to tune setup to acheive the best arrow flight consistently
I disagree. Its even more critical to have proper release with a rest I think because of the contact the arrow has with the rest itsself. A mistkee in release with a seal skin shelf etc allow archers paradox to help elimate that release error.
I've bare shaft tuned quite a few bows and find off the shelf tuning pretty easy and I aint a smart guy to start with !