AppAmaGooBookSoft want few things more in life than for their engineers to remain really, really smart at developing distributed databases and really, really stupid at salary negotiation. They want to avoid further repricing of their entire engineering workforces at once, as that costs (literally) billions of dollars. They take substantial measures to avoid this, including (in recent memory) at least two of those companies illegally colluding against their employees to avoid those employees learning accurate facts about market clearing prices for their labor.

This also helps develop cultural norms like e.g. "We're here to organize the world's information. It is Ungoogley to collect a spreadsheet about Googler salaries. That information should never be organized... by you, that is."