Even for a mammoth like ATandT, the economics of going local are close to prohibitive, because the local loop is the most expensive part of the entire system to build and operate.
Even for large corporations like AT&T, going into the local market can be too expensive.  
mnli hypothesis: Even for large corporations like AT&T, going into the local market can be too expensive.   premise: Even for a mammoth like ATandT, the economics of going local are close to prohibitive, because the local loop is the most expensive part of the entire system to build and operate.