It was written during the time that was the peak of those systems (the endless September would happen a year after the book was published), so there's no surprise there.

But I think it's not particularly accurate, in that, while latency would be extreme, that doesn't necessarily translate to bandwidth - and bandwidth constraints shaped Usenet and especially FidoNet as much as latency.

I think a more likely primary mode of operation would be WWW-like, but only your local part is actually real-time; everything else is synced in bulk as and when possible, with some creative approaches to update conflicts for writable resources.