The "cardless" 6100's and 9200's that have cards are refurbs, and have cards because they have an onboard DishNetwork chip
They were purchased when Dish swapped out MPEG2 receivers and moved to MPEG4, just like Bell is doing now
I think it sounds better when it is said that the onboard chip failed, instead of saying that the receivers were on another satellite system, but are now obsolete for HD on that provider
That would get customers nervous, so hence the "on board chip has failed" story, or at least thats what I think happened