Because the internet was what kept Chris away from both Barb and Bob. Chris spent the majority of time at home, when he wasn't out in the afternoons trolling for booty at the various stores around town. When he was home, he was parked in front of the computer.
Now imagine if Bob really did cut it down. Suddenly all those hours where Chris was busy on the internet, now he's talking to his parents non stop about his stupid shit.
I still have a hard time watching Chris's old videos where he's in his room, jumping around, screaming, making stupid noises, yelling about people being imposters, all the while, on the other side of a few inches of wood and drywall, were his parents. Sitting between mountains of garbage, listening to every word wafting from Chris's room like a foul odor. They probably knew if he wasn't on the internet doing that, he'd be acting like that to them.