This is pure speculation. BUT, it seems to me that platforms have two differences that could, maybe, cause some problems:
1) Platforms force ALL of the power to come on the down stroke. So, at the same power level, more stress would be put on the knee and the muscles than with clipless.
2) Platforms would tend to put more of the force on the ball of the foot (which is the highest part touching the pedal) as opposed to clipless where the force is in the middle and/or spread across the foot.
I'm think that both of those COULD maybe change the way force is applied to the knee as well as how the various muscles are engaged.
I wouldn't bet the farm on it -- but neither would I count it out...