Really what about the SV party culture ? And if the companies are that professional and only care about your work why does the age bias exist ?
What party culture? I worked at Google in Mountain View and never saw any of this, nor "brogrammers", nor endless mandated/encouraged overtime, or most of the other stereotypes that seem to perpetuate themselves.
How long did you work there >5 or >10 years or sth like that or just a stint ?