There are two problems with this point.
1) Federer is an aggressive baseliner, so the reliance on reflexes in that comparison is, shall we say, "unsuitable"
2) Especially in Nadal's case, he has been out of the game for roughly 2.5 years, so that was a time when he could rest mentally, and, obviously, physically.
People underestimate the importance of those pauses for a player with such a style, mainly focusing on his "injuries", none of which left any serious trail, but what they do not account for is that the mental burnout, and physical grind needed to be countered.
Mostly people who are not old enough to remember Borg think that taking breaks from the game is bad.
Recently Federer has (yet again) shown the way for the oldies, but Nadal doesn't have that much time left. I have him at maximum another two years of constantly high level of tennis. After that it is a part time affair or retirement.