Sure, Google/FB/Apple have plenty of money and power, but I don't think they have so much power that they could simply build whatever they wanted without approval.
The coalition impeding affordablity now thrives precisely because tech industry workers refuse to align themselves with the lower classes suffering the brunt of the damage under these circumstances. The ownership class then gets to paint themselves as trying to defend against all these encroaching barbarians that are making things tough for the little folks, all the while profiting from the exploding housing costs. They consolidate power around keeping out the "other," and then turn around and use it to soak tech workers (and by extension their companies) with higher rents. The play the bottom and the middle against each other and stay on top.
The hostility is a ruse, just like it is in politics on the national level, and it has to first be shown for the lie that it is. As an example, what if wide swathes of tech workers held rent strikes until more affordable housing is built for low income residents? Suddenly the narrative that sustains the ownership class becomes less and less coherent, and space is opened up for actual reform.
(I don't actually know and a few minutes spent googling didn't turn up anything conclusive/satisfying.)
Tested and disproven.
Google tried to develop thousands of new units of housing in 2015 and was rejected by the Mountain View city council.