Disclosing your salary to fellow employees helps them by increasing their ability to bargain effectively with their employer. (and disclosing salaries to each other helps both of you)
Similarly, disclosing your salary to a potential employer helps them by increasing their ability to bargain effectively with you.
Disclosing to everyone would do away with the issues raised by the article. If everyone knew everyone's salary, there would be no underwater price-fixing scheme, and disclosing to recruiters would do no harm to you and your colleagues' negotiating positions.
Similarly, disclosing your salary to a potential employer helps them by increasing their ability to bargain effectively with you.