Looks like another love-bombing cult that pushes one of the many flavors of radical optimism.
Optimism and positive attitude can change your perception and attitude and allow you to sometimes see and use opportunities you would miss other and this is good. But objectively it doesn't actually change reality. Rule one is that reality does not care. There are times and situations where all the optimism in the world won't help. It can prevent a realistic view of people, yourself and the world around you. Taken too far a positive attitude can be a drug. A very dangerous drug.
That's ironic. The one Landmark seminar I attended taught exactly what you espouse...reality does not care. It was not a love-fest or hyper-optimism crap. If anything, it was a downer for many. Landmark (as far as I could tell) teaches you to honor your word. Sounds easy? Start making lots of promises and see just how many you end up breaking.
And no, I have no interest in defending or continuing Landmark, but it is most certainly NOT a "think positive to change the world" thing. It's more like a "life hands you crap and you've got to make something good out of the crap."