you can, it has been done already, and apparently it will be in Cp77 as well from what it has been said. You can adjust sway, you can adjust recoil, you can adjust reloading speed, you can have better and worse weapons without going through levels (an M4 is surely more effective than a musket), you can have cyberware that improves sway and recoil, you can obtain new ACTIVE skills from cyberware... Also, it can all be improved by usage without going in a menu and spend an exp point to magically unlock one of these improvements.Cannot reduce accuracy via skills too much
Adding +10% DMG is lazy and useless, doesn't make you feel improved, it just boosts the numbers you see on screen but those are compensated by enemies' numbers being boosted as well by their higher level. Numbers are higher, but the game hasn't changed a bit going from level 1 to level whatever.
I don't want to think that gamers really need to see numbers being pumped up to feel the thrill of progress, when you can actually make your character improve with better abilities and without showing numbers on screen.