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The point was why are they so low, which they aren't.
Moreso, while the Stack of the Surly is consistent, because of the top tube length being irregular to says the least, this mean people end up sizing down and required more headset spacer, which in itself as you said, not a bad thing, but if you add a full carbon fork, there is a limit on how high you can set the steerer too (Specialized Tarmac for instance have a maximum stack of 40mm)
The point was why are they so low, which they aren't, maybe the headtubes could be slightly longer, but to cater for the slammed wanna be racer brigade and the fookin ell I'm over 40 and my back aches brigade, spacers give you the choice (like the height adjustment on a quill stem).
If you don't race why would you want to be folded in half, having to strain your neck muscles to look at the view, I'll go more upright even if it involves a few spacers.