World Cups are why Pele is Pele and Maradona is Maradona...
The majority of Pele's legacy stems from the World Cup, partly because he never played outside of Brazil until signing with the Cosmos, unless he was with the national team. Pele is the greatest World Cup player.
Maradona cemented his GOAT legacy at the 1986 World Cup, with his two goals against England in the semifinals. However many pundits cite Maradona as the GOAT, because he played club football in Europe for years.
The Cruyff argument is also a great one, but mainly because his legacy was largely dampened by his own finicky personality. He could have won two World Cups, but was shaken after the "pool scandal" in Germany 1974. Then he retired from the national team pissed off about 1974, who lost to Argentina in Argentina in 1978. He did great things while at Ajax and Barcelona.
He's definitely one of the most influential personalities in the development of football.
If Messi can continue at his current career arc, with him still improving, he'll be viewed as the GOAT, regardless of World Cup triumphs.
This post was edited on 10/11 at 5:41 pm