system
A chat on subreddit /r/NoStupidQuestions
human
Even if someone has hobbies that take the same amount of time as gaming, they don't necessarily have any time that isn't currently allocated to something. "I have no time" can often mean "I have no time that isn't currently taken up by something I need to do/would rather do/have the energy to do over something else." 

Also, some people prefer to be able to take large blocks to play games and don't have those large time blocks open.
gpt
To add to this, for me personally anyway, I rarely ever sit down and *just* watch TV. If a show is on I'm usually also cleaning because I can watch while also being productive. 

I prefer video games but I can't do the dishes, for example, and game at the same time. It's very easy to see why someone might see gaming as more time consuming compared to just TV.