It should not. My GTX 560 Ti runs Battlefield 3 on ultra without AA settings with 50 fps average. If I set it to high, it runs on 56 fps average (using adaptive vsync, so max it gets is 60).
The 560 Ti is a good choice for the ~250 price range. It won't be maxing out BF3, Skyrim, or anything newer of comparable graphics but they'll diffidently be playable on medium settings.
You're very very very wrong. The only games I could not max out are Battlefield 3 (as I said, ultra with AA) and Crysis 2 (had to reduce post processing by 1 step, everything is set to max). It's nowhere medium settings. Seriously, don't spread misinformation!