Without a doubt optics increase accuracy. IIRC up to 80% increase in a US military study. The study was over six years or so and I lost the link to the report. Good optics can cost 3 times or more then the rifle. It's not cheap. Most people don't realize only a few militaries can equips their entire arm force with optics. The US started their optic program in the late 1990s. It took them almost a decade to equip every troops with optics. It is a long expensive process.