If not for Raf, Fed might well have accumulated 5 RG titles. Yep, he's a very decent clay courter and might well be among the best ever.
You just proved my point. Federer doesn't face the match ups on clay that give him fits apart from Nadal. Look he struggled against proper clay players when they were past their peak, before Nadal was on the scene.
Why cause the surfaces are so homogenised, hardcourt tennis played on all surfaces with the movement being the only difference and who was the best at that?