Thanks for engaging with this. I was intentionally brief in my explanation. I have observed this behavior in congested networks for years and ignored it as an obvious symptom of the congestion. What has always piqued my curiosity though is just how long a ping can last.
In my case yesterday, I was at the airport at peak holiday travel and free wifi usage time. I expect a bad experience. I don't expect a ping to return 5 seconds after originating it. I just imagine the network straining and groaning to get my ping back to me. It's okay, man. Let it go.