It is a way to make sure Chain Blade users have even lower "Grades". Now every time you "Boop" a Behemoth you are guaranteed to go down so that all the high DPS types can rush over and wail on the Behemoth while you slowly get to your feet or you lie dead on the ground while everybody pummels the Behemoth, too busy to waste their time reviving a weak, no DPS producing, loser like you until the Behemoth gets back on it feet. Then they all hide behind you waiting for you to "Boop" him again.
Hey there, our intent was not to lower the grades of CB users. Sorry if it appears that way!