Because it was a lie. Just like when student communists in the 1960's called for "Free Speech".

Leftism is a philosophy of War. They are engaging in a Melian Dialogue. Their rhetoric is not one of compromise or persuasion, it is one of rhetorical warfare. So long as they can trick you into saying yes once, then they will accept that as unlimited consent to any further actions or attacks.

There were more ""conservative"" (read: Evangelical or Neo-Con) establishments at one time, most of those are now dead, burried, or fully subverted. It was during that time when they co-opted the term "Liberal" and when they seized control over 1st Amendment protests.

They always seek to subvert and seize any argument that is tactically useful to them at a given moment. It's not about principles, it's about power. Principles don't guarantee you power, only defeating your enemies does.

Always remember that the May Day celebration that Communists celebrate, is from an incident where Communists set up a bunch of "Social Democrats" to protest for a minimum wage. When they arrived, Communist agitators threw dynamite at the police who were observing the protest, causing the cops to fire on the protesters. The Communists then used these deaths to start riots, and make it a focal point of their international movement. They are always prepared to kill and maim their own supporters even to get an iota of power because they have no principles that they are operating under. Their philosophy is one of War itself.