Most of big tech's major data centers are in Loudoun County, VA on the east coast not the west coast. It's centrally located to be great latency for the east coast and OK latency for west coast and Europe. Plus a friendly regulatory environment and lots of existing DCs (AWS us-east-1, Azure East US 1/2)
If you're feeling any better latency on the west coast it's more likely to be placebo than real.
On the contrary, Big tech famously has plenty of data centers on the west coast:
• Quincy, WA (Microsoft)
• The Dalles, Oregon (Google)
• Prineville, Oregon (Facebook, Apple)
• Hillsboro, Oregon (Cloudflare, others)
• Boardman, Oregon (AWS)
By traffic load east coast datacenters dwarfs these.
The parent comment wasn't regarding traffic loads; it was regarding latency.
Your experienced latency will be heavily influenced by which DC you hit, in which case we care about the relative traffic loads because you aren't just hitting your closest one all the time.