Well, those would be bad interfaces. But the standard in OS X and Windows apps is to have tooltips.
>A further complication is that people tend to copyright icons, so the icons from one app to the next are substantially different.
Is that a thing? They might not be able to show the exact same design, but they'd still be able to show a floppy disk or trash can or whatever.
That said, OSes could (and some do) provide standard sets of icons to be used across apps, and only special app-specific actions should have custom icons.
Some people have implemented icons poorly, so we shouldn't use icons, isn't a compelling argument. Those people might implement anything badly, for instance choosing bad text in a text-based approach.
Agreed re: consistency -- good icon design requires understanding what people expect and matching it, which isn't always easy (as the referenced project demonstrates!)
> x for delete
I've seen 'x', 'delete', 'del', and the trash can. 'x' is also used to cancel or close. There's little consistency.