Following up, from your story, one of the links presented on the internal briefing,
http://i.imgur.com/quf68FC.jpg
Not to mention
http://i.imgur.com/kJkK4HJ.jpg
I would also point to the FCC reports based on their SamKnows test deployment indicating that Comcast customers achieve, on average, >100% of their tier's speeds at peak periods as of last report cycle.
DOCSIS is fine. Virgin Media are being bitten in the arse through not planning ahead with regards to power, space, fibre, node splits. On the upside a bunch of sites have had upgrades completed now, so the capacity will be coming online soon, much to the relief of many.
Comcast are trying to either stem the flow of people leaving their video services but staying with their HSI services to stream OTT, or to monetise that base more. Remember Netflix is close to, if not already at, 40% of downstream bandwidth usage during peak times in the USA. YouTube comes next at ~16-17%.
Given those numbers, alongside that many are using these services in lieu of paying the cable company for video services, and that line rental is essentially non-existent on the cable company's VoIP telephony services, it's not a massive shock that Comcast are trying to monetise the cord cutters more, either via charging them more for the capacity they use or making them pay a premium for unlimited services.