Unfortunately, why it lost is very long and drawn out, and it is actually a series of things that happened over many, many years. But it sort of goes back to the idea that there is regulatory symmetry: what is on one side and applied to cable gets applied on the other side equally on phone.
Years and years ago, when nobody was using resold or wholesale cable, the cable providers said they would like to charge the wholesalers, of which there were effectively none, the same thing they charged in retail, and nobody really objected particularly strenuously--nobody used it.
Well, now Bell has rightly said, “Look, you allow it over there.” Rather than going back and fixing the wrong from many years ago, they used it, and said, “Yes, okay, that's a fair point. We have allowed this for years on cable, so we should allow it on telephone-based services as well, on DSL.” That's why this change.