why don’t we say a bracha before eating the pre- yom kippur meal?
The Netziv answers since the Chachamim said to only say a bracha on the actual mitzvah not on the preparation
Q:So why do we make bracha on shechita and tevilas keilim which is just preparation for the action?
A:Rav Eliashiv says since the pre- meal is a preparation for the fast it becomes the tofel of the ikar(actual fast).By shechita and tevilas keilim there is no mitzvah to eat the animal or to use the keilm rather you need to do these actions to use them first.These mitzvos of shechita and tevilas keilim stand on there own and they alone are the ikar.