It's not as effective. Irans rockets are much faster so they need less of them to break thru, and Irans are actually accurate and can hit launchers unlike the low tech ones. The low tech ones are so slow that the Iron Dome can shoot down tons of them and you have to launch way more to get thru. Iran can launch like under 10 missiles at a launcher and 2 or 3 will get thru. Because theirs are just so fast theres not as much time to intercept them.