Scaring the bejasus out of people for one, especially when they start their racket on "fear". They say they are providing tools, a new technology. But this is bullshit.
As some have spotted, much of what is said in Landmark forums "...being the potential of...." and so forth, comes straight of Heidegger or Gadamer. So it's a jargon based on philosophy and some sociology. (Bourdieu always argued that sociologists were truly therapists. Little did he know.) In acquiring that jargon, as in any field, one feels empowered and different. Or I should say distinguished or distinctive.
Being able to talk a jargon isn't in itself a way of living. I've found if you read enough about what goes on in Landmark, after a while it's easy to pick up the jargon and use it. Does it matter if it's being used "authentically" or with "integrity"? Not really, because no one could distinguish one from the other. After all, that's what makes a con man so effective. (Sociological note: read Goffman's Asylum for a real analysis of a Forum.)
It's the use of this jargon or language which gives the self-rightous air to some. When some family members have gone this way, they can be dismissive of others because they justify all in terms of their jargon. An explanation by someone can be dismissed as "running a racket". Refusing to see the "light" means you are committed to your "strong suit" and therefore not open to the "possibility of transformation". Change by the way is negligible. What counts is "transformation"!
This stuff isn't hard to learn. Spend a little time and you too can fun with your Landmark cultists! Go on, jig them around a bit!