Except if your name is
@KingKyrgios. He said because Sampras is better on 2 surfaces (grass and hard), he is better overall than Nadal. But he forgot to mention Sampras only adapted to 2 of the 3 surfaces. Nadal adapted to the 3 surfaces, winning Majors on each one (hard, grass and clay), therefore showing to be overall more complete.
In short, 16 GS and Career Grand Slam > 14 GS with no French Open.
And all the speculation "if Nadal had played in the 90s" or "if Sampras had played after 2001" is just that, especulation. Untestable claims lack verisimilitude. Claims that cannot be tested are, by their very nature, pseudoscientific. Nobody can prove Nadal wouldn't have won any Wimbledon title in the 90s, when even Agassi did it, and Agassi lacked the velocity and weapons of Nadal. And nobody can prove Sampras could only have won 2 or 3 Wimbledon titles in the post 2001 era, making him a player of less than 10 Majors. Remember a 29 years old Sampras hasn't proved to be able to defeat Roger in fast grass, go figure in the slower grass.