I didn't know what to call this threat to human dignity, I could have went with ideological, collectivist, communist, totalitarian, or revolutionary threat. But I landed on utopian threat.
The threat here is how a collective, utopian vision of the good--the Cause or the Revolution--becomes the altar upon which people must be sacrificed. You got to crack a few eggs to make an omelet. It's okay to trample over human rights and dignity if that's what it takes to build a better world. The ends justify the means. There are sacrifices--human sacrifices!--that must be made for the greater good.
Utopianism is a threat because the Cause is very compelling, it's a vision of the good that is really, really attractive. Evil results because you're pursuing the true, the good, and the beautiful.
Aleksandr Solzhenitsyn's The Gulag Archipelago is a historical case study of how a uptopianism, especially a godless, materialistic uptopianism, comes to erode human dignity.