What was the killer use case of the web?

What was the killer use case of the web? Google.

Google wasn't even imaginable until the web was already deeply underway.

It was a thing that had to do with the specific novel dimension of the web, the thing that was most unlike other systems.

The web was different from software from extremely low friction and ability to visit novel, untrusted content immediately.

So the killer use case was a search engine to make sense of that diverse, cacophonous ecosystem.