You really do not (want to) understand what surround sound is about.
Thats the problem.
The game/movie does not just stay in the television. People, objects, animals and all that stuff can
leave and enter the picture from different sides (they can stay out of the picture and still be there aswell).
Just a quick example where pod racers leave the picture:
Besides that: As a human you also have a limited FoV. Nontheless you are able to hear things around you in a three dimensional way. Just because you do not see it, it does not mean that nothing is there. Thats the same with movies.
Sure youre picture is limited by the television. But that does not mean that the "world inside the movie" ends.
Games take even more advantage of these "effects".
Just imagine you are playing RDR2, riding through a forrest when you suddenly hear the roar of a bear from behind you. After hearing his roar you turn your camera around and suddenly there is a bear right in front of you. Thats the point. Surround sound can increase your immersion. 3D Audio does it even better. With the help of these features you can dive into the game/movie even better. It will be much easier to "ignore" the room you are sitting in.