Google docs doesn’t work?
The things that docs don't have are things like templated designs, and other typesetting features that a professional document creator would want to use. It also isn't completely compatible with office document formats (some formatting and alignments are wrong). I would imagine similar with spreadsheets.
Having multiple people working literally at the same time is an interesting way to work, though not something I want to repeat/rely on often.
They are really stretching what you should be doing with a spreadsheet and they are fully collaborative/multi-user. At some point it got really old to wait fifteen minutes for the sheets to recalculate.
I think it is great for planning a birthday party. Less so for critical engineering documentation when lives are on the line. My experience is that sloppy imprecise tools lead to sloppy imprecise work.