Let's talk about mushrooms, no other similar mechanic in the game lasts after death, shaco boxes/clone, heimer turrets, elise spiderlings, yorick ghouls, among many others.
Because it's considered to be a 'trap' that means it persists through death and lasts the longest in the game by about 8x.
Yes mushrooms bother me, and yes it bothers me that i have to buy oracles for a champ that rarely uses stealth. All because killing the player doesn't eliminate his creations, like it does on every other champion with similar mechanics.
It's very rare when any team goes about getting oracles for an AP shaco, because his jack in the box traps are owing people. And when I say rare, I'd bet that's never been a case.