Should we believe any parenting advice?

After all the fads in early childhood development, on p. 235 of Judith Warner's Perfect Madness, there appears to be some sane advice. But why should we believe this when we already bought into attachment theory (our children need to be "securely attached" versus "dangling loosely")? In the end I think these statements were selectively used to support her notion that hyperparenting is bad:

... overmothered children were showing "an inability to endure pain or
discipline or pursue any self-sustained goal of any sort." In 1978, Psychology Today argued that overprotecting children might deprive them of a chance to develop a sense of control over their environment and breed a kind of "learned helplessness" -- a habit of giving up in the face of difficulty. By doing too much for their children, overly solicituous parents could make their kids believe they were unable to do for themselves. "Comfortable levels of stress," the magazine warned, "may be better for a child's ego development than things that happen without any effort on the child's part. Self-esteem and a sense of competence may not depend on whether we experience good or bad events, but rather whether we perceive some control over what happens to us." ... Bruno Bettelheim warned that the overbearing boomer parenting style was keeping kids from having sufficient mental room -- or spielraum, as he called it -- to develop a rich inner life. This lack of an inner life, he warned, would eventually lead to a situation where children needed constantly to be entertained -- either by parents or by TV. In 1996, family psychologist John Rosemond wrote that children were suffereing from "hand-and-foot disease, which is usually prompted by being waited on by an overly solicitous parent, usually female." The symptoms of this ailment: "Today's children whine more, are more disrespectful, and throw tantrums long past the age when yesterday's children were over them completely."

I'm tempted to dissect and play devil's advocate to each and every statement above but that would be too easy. In the end, I probably don't know much more about parenting today than I did 8 years ago.