In the United States, at least, telcos seek to exercise a lot of muscle over the services using their pipelines. Way more than the water company does over the pipes, as it were. Specifically, telcos may charge customers more just for service sufficiently stable and fast to support Ninty's or Sony's or MS's online platform. There are ways they could hold such uses hostage and either charge customers more or ask for payouts from the platform providers.
Besides, offloading the risk onto consumers may not make sense; folks may rather have a stable gaming platform out of the box than deal with the risks offloaded onto them by a digital platform.