This was before Facebook broke the SV no-poaching ring, so the offer probably wasn’t that spectacular. Also, in 2006-2010 any RSU’s would be rather horizontal.
I don't know what "horizontal" RSUs are, but they were options back then, and every year, you got a bigger (more value) pile of them. My total comp doubled without me getting a promotion in roughly 5 years.
Today: $2500