Why Yorick stays bugged ? This ain't a final answer at all, only a theory. But I believe that if all of Yorick's bugs got fixed, he would be broken. I'm not that good at Yorick (digging my way to mastery 6 right now) but I believe that fixing every bug (especially making ghouls apply on hit effects correctly) would be insanely good. I don't mean it was meant to be, but that maybe now Riot is stuck with leaving bugs and making Yorick very situational (but still an insane splitpusher) or fixing the bugs and ending with a bulldozer army instead of a monk with a shovel. This is just my personal thoughts, would love to debate this in the comments !