Does this apply to a Gmail or EC2 console kinda usecase? Going back to a previous version is essentially pointless because the state of your inbox/instances has already changed and that page is stale.

Oh yes, indeed. Please implement it well or of not don't implement it at all. Nothing is as annoying as reading an article and having it snap back to the beginning, or suddenly staring at an error page.

Sure, for console-like applications like EC2 you cannot do without auto-update. However, on content sites that require longer attention to one piece of information, it is not necessary.

Not really. There were other hypertext systems at the time, but the early HTTP and HTML were clearly the minimum viable product that kicked off the progression towards what we have today.