Ajax took off after that. It underpins major parts of modern web development, and has spawned a number of frameworks and methodologies. The technology itself has been swapped out over time. XML was replaced by JSON, and XMLHttpRequest by fetch. That doesn’t matter though. Ajax showed a lot of developers that the web wasn’t just about documents. The web could be used to build applications. That might seem like a small notion, but trust me when I say, it was momentous.
I love Ajax, but it absolutely must be employed as progressive enhancement where possible.