Sometimes saving is a high latency operation.
Sometimes you don't want to show others data as it is being edited, think product data for an online story. Heck the "reply" button beneath the text box I'm typing into right now is a form of "save".
Paradigms matter! Saving was necessary for all disk IO for a long time due to technology limitations, but even now days it is still the appropriate paradigm for certain circumstances.
In modern CMS workflows (used by e.g. newspapers), the software will auto-save draft versions; while you then explicitly publish particular versions (or, more likely, submit particular versions for the next stage of the pipeline, e.g. editing) by changing your latest version's state in a drop-down.
This process really has no analogy with saving per se. It's more like tagging a commit.
I'm someone who does everything that I possibly can while offline, and I'm mostly in the camp that the "Save" button being a floppy is not much different today than learning how to pinch-to-zoom or click a mouse (i.e. there's an up front cost to learning it, but it's already ubiquitous, so why change)