I think it basically all stems from overselling ahead of infrastructure capacity. ATTBI took a core (and merely testbed) network built for 1500 test users, and ramped it up to over a million users in only a couple of months. Then mergers start happening, which actually ~slows~ the process of massive systems projects by causing all sorts of confusion and re-invention of departments.
They've just never caught up, and the overselling continues so the goal line keeps moving.
DSL providers are in the same box.
;-)