By some felicitous fluke I still have the very first html I ever coded, anno 1995, complete with background sound and animated gif - but cut me a bit of slack: It was purely a personal excercise. The thing was done purely from what I'd learned studying source of available websites. The point being: My God, it's full of tables. They were a real thing by that time.
PDF documents have tables. Documents are things meant for a human, it's not raw data, for computers to understand it you need machine learning.
Applications are not based off documents but rather the raw data (which the machine natively understands).
The transition of web from documents to a dumb platform for application software delivery is why the web is no longer the web. It is just application delivery infrastructure now. Each application lives in a walled garden and is no longer a "web" at all.
Sure, of course it was. But the web was almost entirely a collection of documents back then.