Also it didn't matter that Sampras had 0 RG titles when he became the all time slam holder.
Therefore your comment about Nadal being a distant third on grass or HC means nothing.
I trust that since the 1990, our analysis as become more refined and rigorous. I trust no one would make the mistake of overlooking Sampras' RG futility and not-so-impressive Super Nine record (as well as rather poor Davis Cup). Not that I am sure such things were not mentioned at the time. When Sampras broke "the record" - a record even the record holder did not realize was a record, or something to be coveted - the talk was that Sampras was one of a handful of "greatest". Some sports writers may have suggested he was the greatest, but I believe at that point Laver and Borg were rated above Pete (and, of course, two or three or four other contenders had begun to be forgotten - Tilden, Budge, Gonzalez, Rosewall).
Thanks in part to our forums here on Talk Tennis and the interchange of ideas, I believe we have a broader set of criterion than simply number of Slams. Nadal is incapable of winning an indoor title. His indoor record is worse than Sampras' clay record.
Clay is my favorite surface. In the game's history, it was a close second to grass for the pre-Open amateurs, but not used that often among the Pros. In this century, Clay has become considerably more important than indoor, with with RG and 3 M1000s versus one M1000 and the YEC.
Where does each of the big three land on each surface or condition is one interesting way to look at their relative merits.
I list here what I submit are quite plausible lists of top-20 players by surface. I am not fixed on the rank order, or I may well have left someone off who is deserving. On Clay, there are close arguments for those last few spots. But that is irrelevant. This is to see where each of Federer, Nadal and Djokovic rank by surface.
CLAY
Nadal (1)
Borg
Cochet
Lendl
Rosewall
Laver
Kuerten
Djokovic (8)
Lacoste
Tilden
Drobny
Cramm
Wilander
Trabert
Courier
Federer (16)
Gonzalez
Gimeno
Nusslein
(tie) Vilas, Ferrero and Riggs
GRASS
Tilden
Laver
Federer (3)
Sampras
Djokovic (5)
Budge
Borg
Hoad
Becker
Rosewall
Gonzalez
Newcombe
Perry
Lacoste
McEnroe
Sedgman
Edberg
Connors
Cochet
Kramer
Nadal (22), behind Murray and Ivanisevic.
OUTDOOR HARD
Djokovic (1)
Federer (2)
Gonzalez
Connors
Agassi
Lendl
Budge
Sampras
McEnroe
Kramer
Nadal (11)
Vines
Perry
Laver
Gonzalez
Tilden
Courier
Sedgman
Rosewall
Johnston
INDOOR (generic, not parsing by surface, but obviously in 1970s-90s, this is majority carpet. For the pre-Open pros, it is wood, hard or canvass over ice or some other surface).
Gonzalez
Laver
McEnroe
Lendl
Rosewall
Kramer
Sampras
Becker
Borg
Djokovic (10)
Ashe
Vines
Budge
Borotra
Federer (15)
Hoad
Perry
Sedgman
Segura
Newcombe
RESULTS:
FEDERER: Clay (16);
Grass (3);
Outdoor Hard (2);
Indoor (15)
NADAL: Clay (1);
Hard (11);
Grass (22);
Indoor (no and not close)
DJOKOVIC: Clay (8);
Grass (5);
Hard (1);
Indoor (10)
This is merely one of many tools we can use to analyze where the Big Three stand. All legitimate methods should be looked at and considered. But this notion that if Nadal wins two more Slams nothing else matters is misguided, IMHO.