totalitarianism is integral to liberals because they incorrectly believe they are far more intelligent than anyone else and especially the stupid people that hold opposing views, and because they believe this, they believe that they can achieve their goals by any means necessary - the ends justify the means.
Indeed. C.S. Lewis was thinking of folks like Parker and her fellow travelers when he wrote this:
“Of all tyrannies, a tyranny sincerely exercised for the good of its victims may be the most oppressive. It would be better to live under robber barons than under omnipotent moral busybodies. The robber baron’s cruelty may sometimes sleep, his cupidity may at some point be satiated; but those who torment us for our own good will torment us without end for they do so with the approval of their own conscience.”