imagine for a second, you're a positive ET. you come across Earth, being ruled with an iron fist by kike bloodsuckers and negative ET's but the population of the planet is unaware of the problem. do you come to Earth, fuck shit up then stand back and say "alright guys you're free now!" ?
of course not. you'd be seen (by the people who thought the world was changing for the better) as conquerors and oppressors. this is where individual/independent contact comes into play. if you can maybe show enough of the population that you're not horrible intergalactic demons, maybe it'll be their idea to have you come fuck shit up for them. its all about free will my dude