Now, we have three Roku TVs and two 4K AppleTV boxes (thanks to DirecTVNow). We subscribe to Netflix (free with T-mobile), DirecTVNow, and Hulu.
My dad came up and he loved our RokuTV so I bought him one. He likes it, but he would never go cable free.
With cable, you just turn it on and start watching. With the Roku TV, you have to sign up for an account, add channels, login to all of your subscriptions. If you have cable, you have to login to all of the different channels with your cable subscription. WiFi is also more flakey then cable. Then on top of that, they have to worry about going over thier 400Gb cap.
Can you imagine most 70+ year olds having to go through all of the hassle with five TVs? Heck, except for the RokuTV, all of thier TVs are CRTs, including one that I bought for myself when I moved out in the mid 90s.