And yet it is still so easy to imagine such an outcome. Actually, I am more surprised that they chose such similar roads more than they are close in achievements. For example, maybe Vulcans would have made breakthroughs in areas that have no value for Romulans, and viva a versa.
That the Vulcans and the Romulans have incredibly close levels of technology is surprising, yes; but not nearly as surprising as the idea that the Humans, the Klingons, the Betazoids, and about a hundred or so other species all have such incredibly similar technology levels, and all without any hint of shared history before they developed their seperate warp drives.
Here's another installment of rationality quotes. The usual rules apply: