OK, but I think it was Google Maps that made the experience of not needing to refresh the page popular (while being shown more information from the server).
For a long time, you needed an invite to sign up for Gmail, so you couldn't easily share the cool experience of AJAX with others like you would with a Google Maps link.
> it was Google Maps that made the experience of not needing to refresh the page popular
IMO that's a reasonable impression of the times unless I'm forgetting something (and the additional observation about sharing--"virality" as it was called, before you know--was insightful).
At the time the previous "state of the art" was something like MapQuest which IIRC had a UI that essentially displayed a single tile and then required you to click on one of four directional arrow images to move the visible portion of the map, triggering a page load in the process (maybe a frame load?).
Yahoo! also "participated" in the mapping space at the time.
In the event anyone's interested in further ancient history around the topic, this page is actually (to my surprise) still online (with many broken links presumably): https://libgmail.sourceforge.net/googlemaps.html
(It's what we did for fun in the Times Before Social Media. :D )
For a long time, you needed an invite to sign up for Gmail, so you couldn't easily share the cool experience of AJAX with others like you would with a Google Maps link.