I think you misunderstand the real purpose of these major companies fighting to hire as much talent as possible. Anyone in the Bay Area that cannot afford FAANG total comp knows how hard it is to hire top engineering talent. This is the end goal of these companies hiring policies: to remove talent from the market.
Before these companies where FAANG most of them were small, crazy startups that were able to easily acquire talent because tech was pretty boring at the time. You could pay market rates, but give someone an exciting project and they'd join you. That allowed all of these companies to completely disrupt the market. Having disrupted the market they are no longer interested in this happening again.
The current hiring practices are to basically drain talent from the startup pool. Paying an engineer 500k is much cheaper than acquiring the new darling startup they ended up creating (DeepMind), which is much cheaper than acquiring the now large company that is threatening you (instagram), which is still much cheaper than allowing existential threats to you to eventually IPO.
There's the added benefit that you now have a bunch of great engineers on your team, but this isn't the real purpose. The tech giants of the past, IBM, Oracle etc all failed to realize how important it was not only to have good engineers, but to also remove great engineers from the market.