It amazes me that, under the right circumstances, the wiggle room can reach levels as high as 50%. I wonder what they were thinking when they made you the initial offer.
Recruiters are not going to assume that you can enter any FAANG at the highest possible level. It was incredibly lucky from the OP to get 2 offers and at the same time.
Not sure I agree there. I think it could be a deliberate way to engineer the process to create a leverage which most savvy candidates learn to do every time they're on the market. I've been doing this for the past 6 years. It just takes discipline, casting a wide net with a lot of firms in the initial interview process, and being thorough.