Many people do, but still prefer to watch it via their local affiliates whenever possible. I am even more picky. I subscribe to an IPTV and can stream virtually anything, but would like my local stations to carry every Dallas game.
It is my OCD when it comes to live games. My preference is due to delay. There is notable delay with streaming that is not associated with over-the-air reception or via cable. I have even observed delays according to how fellow members post in a game thread. Sometimes, posts will comment about a down that happened two, three or more plays before as if they were commenting about the previous down.
It even grinds my gears if every trick I can find reduces the delay to a few seconds. The fact that others have seen what I haven't yet is annoying to me. Streaming is an option for everyone, but every person may have their reason for not choosing it too.