Passage One 　　
Questions 56 to 60 are based on the following passage． 　　
The endless debate about“work—life balance”often contains a hopeful footnote about stay at home dads．If American society and business won’t make it easier on future female leaders who choose to have children，there is still the ray of hope that increasing numbers of full—time fathers will．But based on today’s socioeconomic trends，this hope is，unfortunately，misguided． 　　
It’s true that the number of men who have left work to do their thing as full—time parents has doubled in a decade，but it’s still very small：only 0.8％of married couples where the stay—at—horne father was out of the labor force for a year．Even that percentage is likely inflated by men thrust into their caretaker role by a downsizing．This is simply not a large enough group to reduce the social stigma(污名)and force other adjustments necessary to supporting men in this decision．even if onlywork more than their family． 　　
Even shorter times away from work for working fathers are already difficult．A study found that 85％of new fathers take some time off after the birth of a child—but for all but a few．it’s a week or two at most．Meanwhile，the average for women who take leave is more than lo weeks． 　　
Such choices impact who moves up in the organization．While you’re away，someone else is doing your work，making your sales，taking care of your customers．That can’t help you at work．It can only hurt you．Women，of course，face the same issues of returning after a long absence．But with many more women than men choosing to leave the workforce entirely to raise families，returning from an extended parental leave doesn’t raise as many eyebrows as it does for men． 　　
Women would make more if they didn’t break their earning trajectory(轨迹)by leaving the workforce，or if higher-paying professions were more family friendly．In the foreseeable future，Stay at home fathers may make all the difference for individual families．but their presence won’t reduce the numbers of high potential women who are forced to choose between family and career．

Why does the author say the hope for more full—time fathers is misguided（）