Yeah, it never made sense to me: If it should be read as in the next house then why isn't the boundary over there?
And then I learned the history of cuspal uncertainty, and it verified my doubts: It comes from the modern era, before computers and easy chart calculations were available but astrology was back in vogue. Basically it's another thing to blame on newspaper horoscopes. Because the sun sign turnover would happen at a particular time, but it was very time consuming, and therefore expensive, to figure out the exact time (not to mention the exact time for anyone born anywhere around a change) the idea of, "Well, just read both that might fit you," became the popular position.
So in short, fuzzy cusps originate as a work-saving/cost-saving measure.
Yeah, with technology being as advanced as it is right now, I don’t think we should follow the blurred cusp concept for signs and houses