Spoil of War?

i've just played a rank game where adc wouldn't let me get any of spoil of war. i was and adc was when i try to last hit he'll keep pinging me to back off. when i ask why he isn't letting me get any, he said for me to last hit. so i'm just sitting there thinking wtf, i'm thresh, i'm not going to be able to beat you at last hit if you're not leaving them for me.

so do players still don't understand how spoil of war works or something?