Well, part of my "training" in gaming is playing games in "concentration mode". Actually, I can't play many games in a relaxed state, sitting on my couch, laying back. That way I always have the feeling to underperform, even if I don't play any competitive or at least challenging game. I'm so used to sit at a desk in front of my PC monitor, being full concentrated and in a position (imho) best suited to perform optimally. That may sound strange to some, but I can't imagine playing a game like Witcher sitting or laying on a couch with a controller in hand. The only games I play on my big TV on the couch are sports games together with my friends and even then I very much tend to sit in an upright position with the arms at least lying on my femorals to get some stability.
For me, games require and deserve full attention and concentration. And I can't imagine for myself being able to get the most ouf of it being somewhere else than sitting in a comfortable chair in an upright position at my desk right in front of my monitor with my arms resting on mouse/keyboard which are based on "solid ground" for maximum stability. That's how I game. So it's not just that I'm used to use mouse and keyboard, I'm also used and "trained" to game at a desk in full concentration mode. It's (at least for me) something very different to e.g. watching TV in a relaxed state on my couch. Completely different form of how to consume entertainment.
Bottom line: I don't feel comfortable playing on a couch in front of the big screen with a controller because I miss both mouse/keyboard as my control input of choice that I'm used to and my whole desk/chair/monitor setup that enables me to fully concentrate on the game and the challenges that may lie ahead of me...
