Experience cannot make up for declined movement and groundstrokes.
Fed's groundstrokes never were that good to begin with. And he's still moving fine.
Then Rafa will be dominating the tour when he is 33, right?
Not comparable -> different gamestyles.
Also on "think as fast," your reaction time and your thinking does slow down as you age. Take chess players. Even Garry Kasparov admitted that as he aged he couldn't keep up with the young guys. Staying concentrated all the time gets much harder, so mental lapses become more prevalent. Roger is playing at a very high level but his prime is passed. Get real.
We're talking about a guy who is 33...that is still very young. Tennis isn't chess. Tennis is about the right tactic and that comes with experience.
The only valid point you made was about the longer recovery time...which is mainly about off-court work but comes into play at longer matches e.g. Slam tournaments. Certainly not here in Dubai.