Both the player and the character matter. That's why so many of the top players choose top 10 characters...because by being one of the best players in the scene and using one of the best characters in the game, it gives them the best opportunity to win. If the character didn't matter, than why doesn't REO go in a tourney with CSZ and win? Why are so many people picking up Kabal and Lao then? It's like if a pretty good driver in an Aventador and Michael Schumacher in a Prius raced for 1 lap around the Nurburgring. You think Schumacher's experience is going to overcome that fact that he's driving that POS? No.
I don't know what kind of fantasy world people think we live in. If you're an American born into a wealthy family, you will very likely be more successful than a Kazakh who comes from a poor family and works harder than you. If you want to be a professional basketball player, you have a higher chance of making it if you're 6'8'' and pretty good than if you're 5'4'' and excellent. If you're a decent tennis player whose dad is Roger Federer, you have a way higher chance of going pro than someone better than you who has no famous family members. And if you play Kabal and train pretty hard, you're more likely to succeed than a Stryker player who trains extremely hard. It's not just one thing that matters here people...this is just the way life works. Is it right? No. Is it fair? Of course not. But it's the truth.