If they weren't there would be no point in having a 30fps (now 60) FPS cap with medium graphics. If you look at how a game runs on PC vs. console it's very clear that PC will always have the potential to function better. Another thing to think about is that consoles use the same hardware for years and developers have to make sure games can run on 8 year old hardware until new consoles come out, where on PC once a part gets outdated you can just replace each individual part as you need.