Doesn't make any sence. You could just as well say that Rafa would not have won half of his RG titles without modern racquets. If he was to play back in the day, he would not be able to produce half of the RPMs on his groundstrokes that he does with todays' racquets. And, as a result of that, he'd end up losing his biggest weapon(by far), his top spin forehand. Consistency would drop, as would his ability to return balls with interest from impossible positions.
Point is. A player can only be the best at what he's given the chance to be the best at. Fed does not walk around saying to himself"****. I have to play like Pete and become better than him at S&V. If not, then I'd stand no chance against him if someday, a scientist was to invent a time machine and send me back to play against him on 90s grass, in his peak. ****. ****. ****!!! I hate myself. Mirka! Give me a beer." No. He's focused on becoming as good as possible on the grass that he's playing at!!! His goal is to beat the players that he has to play against, in the conditions that thet have to play in. He doesn't care about the past. Simple as that.
This thread is pointless.