There’s a key difference: nobody thinks playing a game is practicing for a real career as a space marine or heroic paladin. There’s a ton of research published about how teenagers and young adults do pick up unrealistic or even harmful ideas from porn because, unlike almost all games, it is depicting a part of life they will actually practice. Worse, various sex negative cultural beliefs mean that there are a ton of people who are not getting countervailing information – you could argue, for example, that teenagers playing GTA encourages bad driving but they will have good examples from their parents & neighbors, classes, etc. explaining how it really works.