Parental discipline is one thing, but the tactics described in this article go far beyond “discipline”. Chua did not simply put her daughter on a time-out, or swat her on the behind for misbehaving. She withheld food, water, sleep, and toilet privileges. She threatened her child with physical harm. Unless you are claiming that such tactics are appropriate forms of “parental discipline”, then your statement does not apply.
Those ‘tactics’ as you liberals describe them are absolutely acceptable forms of parental discipline, and you should learn how to mind your own business when it comes to how other people raise their own children.