This said, I do think the way yanking rectangles works currently is not
fully satisfactory, because it's not always clear/intuitive how where
the rectangle will get inserted. So maybe we do need a special yank
command active during `rectangle-mark-mode` which replaces the selected
rectangle with the yanked one, or something like that.
I agree. Once I tinkered with yanking rectangles a bit, it (mostly)
made sense to me, but instinctively, I wanted to select the rect to
yank into first. That works as you'd expect when the point is at the
beginning of the rect but not when it's at the end. I'm not sure what
I'd want to change though, since it works the same as yanking when you
have a non-rectangular region selected too.