If you actually want to use scatter shot, in lieu of damaging skills, then you need to make sure your timing in its use is right. If you see a knight about to use his/her Agoran shield, and a mage about to use suntoria, wait until the mage uses the suntoria before using scatter. The server generally prioritizes all party effects over single person effects, so a lv. 1 scatter shot will remove the suntoria. Yes, the knight will still have his/her shield, but they're also not gaining 4-6% of their HP back for 5-7 turns. And since the other members don't have suntoria also, they're more open to pure damage.
Scatter shot also can be a waste. If the opposing team has an archer with battle prowess, which you also have, scatter will remove the battle prowess effect, but it can be very easily replaced since BP is a passive effect.
Overall, not many archers carry scatter shot for a couple of reasons. It's generally not worth the 20-30 rage use since 1: Most battles don't last long enough for it to be useful, and 2: Most effects can be fairly quickly reset.