@wbond This particular issue has been a concern of mine for quite some time. Editing because accidentally hit Tab before Space, which posted early
Basically, sublime puts buffers (manifested as tabs) "inside" splits, whereas VIM (and Emacs) manage buffers at the level of a window, and splits are within that. The critical practical distinction is that you can split as many times as you want, and you have the same buffer set everywhere. Closing a buffer in one split closes it in the others. Opening a buffer in one split opens it in the others (though, traditionally does not give it focus in anything but the one you're currently working in). There is no notion of a split pane which has anything less or more than the same set of buffers that are in all other splits.
Origami does a good job, but it is fundamentally incapable of emulating this element of VIM/Emacs buffer splits, which is deeply, deeply unfortunate and results in a split pane functionality which I find considerably less useful than it otherwise could be.
So it's not really about space loss; it's about how we interact with the editor and the model we need to keep of splits. With "the Sublime way", I have to keep track of which buffers are open where. If I want the same file in multiple places, I have to copy the buffer. Unsplitting with dirty buffers can actually prompt me to save, which is intensely unintuitive. With "the Emacs way", I can just split whenever I want separate views into the same "set of data", and unsplit when I don't want those views anymore.