> Which means Comcast has your current address. It is not hard to look up, in their own database, a name when given an address from a rental listing website.

Yes, this is exactly what I imagined, which is why I wrote, "I suppose Comcast could deduce their customers’ behavior by scraping rental sites," but perhaps it wasn't totally clear.

> Their marketing department likely saw it as a "customer retention" activity. By offering to make the transfer of your Comcast account to your new location easy and effortless (they hope) their belief would be that they might retain you as a customer.

This makes sense.