oracles elixir

I just wanna know y riot removed it from rift i mean a whole team has to buy sweepers and pinks for one champ now when they could be warding the map but no they have to fear that one champ like rengar all u adc mains know what i mean sweeper last only for a few seconds after that bye lol then u have teemo shrooms and shaco and the list goes on its a buff to them or anyone with invisible ability like i said i just wanna know y they took it out