I think your hypothetical attractive 23y/o woman who goes into the office of a middle-aged manager who barely knows who she is and comes out with a better job will be very much rumoured to have "exploited" her "sexual 'assets'", whether she has or not, and that in itself is dangerous for her social status.

I'm also not totally sure that youth is such a negative for a man's social status in the workplace. I can think of a few charismatic young men I've seen get disproportionately (disproportionate to performance) far up the ladder. And maybe I'm mistaken, but terms like "rock star programmer" seem to invoke the cult of youth - in my mind it implies a hip young gunslinger.