said by pipdipchip :

They've always done this. It has nothing to do with digital services really. Comcast isn't going to spend the effort to filter analog out of the other services. Sign up for high-speed cable and you'll be given cable for free. Not as part of any deal.

said by MadMANN :

Inaccurate. They do have traps that filter all analog channels for those customers who sub to data-only services. There was a period of time where many cable companies only trapped expanded services for those customers. In that case, the sub could split their line to a tv and get basic cable. However, most systems now trap out all unencrypted video frequencies and analog services. That's not saying there isn't a tech here and there that forgets to put the trap in place or is just too lazy to do so.