That statement is categorically false. One simple example is online gaming/MMOGs where a latency of 200 ms would be be a miserable experience. The upper bound often targeted for "acceptable interactivity" is somewhere between 100-130ms.

(1) I excluded gaming as something that is legitimately ping dependent

(2) You can achieve 100-130 ms latency with a "like one data center per continent" sort of network. You don't need edge computing on hundreds or thousands of edge sites to achieve that.

I'm sorry but what are you talking about? Fastly has about 60 PoPs (physical locations). No one is talking about hundreds of thousands of sites. Even akamai, who made it one of their primary marketing metrics, only ever got into the thousands.

The GP is talking about putting them in cell phone towers.

Your numbers are wrong but your line of reasoning is actually the basis of how Fastly's network was designed to be different from Akamai's. There's a graph about it at the 2:40 mark in this video: https://vimeo.com/132842124

That presentation was refreshingly honest and interesting to boot with.

200ms is human reaction time, you can definitely notice it; the rule of thumb is 100ms https://www.pubnub.com/blog/how-fast-is-realtime-human-perce...

Your cite says that < 1s is "for users to feel they are interacting freely with the information". Even a 400ms round trip is well within that limit.

Most, if not all websites require more than one round trip.

HTTP2 can reduce this significantly.