secrec
You're right. I'm far off with thousands or even hundreds.
I wasn't thinking about having servers directly on a backbone greatly cuts latency concerns.
My mistake was multiplied by the fact that I was foolishly prioritizing latency to be on par with quad9 or google.
We can trade speed for privacy.
I think quad9, cloudflare, and google are the only ones in the thousands of servers.
Just handling the load isn't enough--hardware failure and maintenance windows are a concern.
Apps and websites often require 4 or 10 queries from 1 click. 40-90ms for 1 query is okay but borders noticeable lag if any higher.
The #1 reason--i think--is because there are other services filling the space such as quad9 or adguard dns.