[bambax]

I think what happened is, liberals learned from conservatives that it's much more efficient in the short term, to make the voicing of an opinion a crime than to fight it on its merits.

Censorship is as old as organized society. Historically, the power to censor belonged to those in power (the Church, royalty, etc.) But it was never exercised openly, it always rested on some higher justification (to prevent offending God or upset the social order). And so, censorship, which is always, in effect, an instrument of domination, somehow became "the moral choice".

At some point (I'd say, fairly recently, sometime in the 70s) minorities fighting "the Good Fight" (tm) discovered the power of moral censorship and they are now basking in it. But it's a double-edged sword and it's very difficult not to cut yourself when using it.