I don’t think anyone called those “web apps” though. I sure didn’t.

As I recall, the phrase didn’t enter common usage until the advent of AJAX, which allowed for dynamically loading data without loading or re-loading a whole page. Early webmail sites simply loaded a new page every time you clicked a link. They didn’t even need JavaScript.

The term "web app" hadn't been coined yet but, even without AJAX I think in retrospect it's reasonable to call things like the early versions of Hotmail and RocketMail applications - they were functional replacements for a native application, on the web, even though they did require a new page load for every click (or at least every click that required network interaction).

At some point, though, I'm pretty sure that some clicks didn't require server connections, and those didn't require another page load (at least if js was enabled): this is what "DHTML" originally meant: using JavaScript to modify the DOM client-side, in the era before sans-page-reload network connections were technically possible.

The term DHTML definitely predates AJAX and the existence of XMLHTTP (later XMLHttpRequest), so it's also odd that this article writes a lot about the former while not mentioning the latter. (The article actually incorrectly defines DHTML as making possible "websites that could refresh interactive data without the need for a page reload" - that was AJAX, not DHTML.)