It basically codifies the idea that female competence is only acceptable in service to male success. On one hand, the trope of the unsung competent person rescuing the incompetent can be empowering and played for laughs in a constructive way(I'm a dude, but I totally wanted to be Penny from "Inspector Gadget"). Tropes are never inherently bad.
But in "Silicon Valley", Monica exists solely to further other people's success, and specifically the success of male characters. She has no agency of her own- Penny saves the world without credit because she actively wants to save the world. Monica advances male careers because... she's good at her job?
Worse, male characters that embody the stereotypes of socially incompetent man-child geniuses. Female characters break down into two aspects of femininity in SV- Monica, who is the maternal, giving, and kind one, and everyone else, who is a sexpot to be ogled.