Communism:
Pol pot, Stalin... Mao to name a few.
The Holodomor could have even exceeded the Holocaust in sheer death.
if you need context, Stalin basically forcefully starved Ukrainian into submission to reduce nationalism and break the spirit of the Ukrainian people (Heh, funny.) and killed about 2-7 million.
Mao's "Great leap forward" Killed over 40 million.
And Pol Pot... I don't think I need to go further.
all that Bloodshed in the name of a imposable task to perfect humanity.
Socialism:
Stated goal is communism, and the spiral always ends in mass death.
Progressivism:
assumes things are banned for no reason.
The Nuclear family is an example. it assumes people are oppressed by systems, not other people.
but in truth, any system can be oppressive if evil people at the head of it.