Unpopular opinion: I believe that kills should not give gold (so no shutdown gold as well)
If you get a kill, even with no reward you can still apply pressure via getting ahead in cs or damaging towers or taking neutral objectives. There will be the best fix for the massive snowballing problem plaguing solo queue.
Plus, since riot is committed to making this an esport. In regular sports, there is no snowballing. Your quarterback does not get better aim and faster for scoring a touchdown.