The difference there is that Bill Gates was not already married. The difference there is that the role of product manager is much more skilled than the position

The difference there is that Bill Gates was not already married. The difference there is that the role of product manager is much more skilled than the position of secretary. A product manager has the freedom to take the lead on big projects. A secretary is such a submissive and typically gendered role that companies have started to shy away from using the term at all. Now they are opting for "assistant" instead, implying a more equal footing between the employer and the employee.