> actually central to document processing?

ahh, the no true scotsman style of logical fallacy.

Document processing is not strict nor defined. The features listed in the parent comment are all very useful, and if the floppy disk document processor of 30 years ago could do it, the people there would also find it useful.

Yes they would find it useful, but in terms of productivity what's it worth? For the things that aren't collaboration, it's probably single digits. Real-time collaboration is worth a lot for certain documents, but also you could have managed that on a 486 if you had a modem.

Literally 100% of the documents I process are sent to other people. So collaboration and sending documents are core functionality.

It’s even stronger than you suggest, the actual “word processing” bits turned out to be a vestige of a paper world and “collaborative text editing” was actually the killer feature.

I wonder why we use paper layout on Word/GDocs despite it never be printed.

All of it, what do you think isn’t?