You miss the point completely.
The point was that there is an argument if you stopped Xavi from controlling the game you could reduce Barcelona's ability even more than if you stopped Messi. And so it's not as simple as to say Messi was the biggest reason for Barcelona's dominance, there is another argument regarding Guardiola's tactics, there are simply too many variables.
To be fair to Messi, in Messi's prime he was up against the golden era of Spanish and German football, great players who never win the world cup are still seen has some of the greatest, and Messi's achievements should not be tainted, when certain era's happen that even a great like Messi could not overpower the great teams Spain and Germany have built.
With all the glory pele receives because he has won a world cup, he was part of a golden generation of Brazilian football. If messi had the standard of that team pele or zidane played in with argentina, messi would also lift that world cup. It is not really if a player was that great, its the team he has got around him.
In a world cup the team wins the world cup not the player, and many expected messi to turn up in Brazil score 8 to 10 goals in a world cup tournament and lift it, that does not work in international football has ronaldo as found out, its about the team not the individuals. Many call maradona a great, he still had a bit of luck against England with that hand ball. But for people to expect messi to destroy one of the most well oiled machines in Germany, have been in fantasy land for way to long.
To be fair to Argentina, Germany's semi final victory over Brazil was a huge boost in their physical preparation, they got to the final within 25 minutes and they played a day earlier. You look at Argentina, they had to slog it out hammer and tongs for 130 minutes with Holland and play a penalty shoot out, and they played a day later. So for Argentina, it was physically and mentally exhausting. so Germany did have that bit of luck you need it to win it.
On the other hand, this is perhaps Germany's greatest world cup victory, their group and knock out fixtures was pretty impressive, and they won it in south America in that heat wave which is huge for a European team
Germany's scalps
Portugal
Ghana
US
Algeria
France
Brazil
Argentina
So not only was their road pretty tricky, they beat the 2 south american powerhouses in the semi's and the final in south america. They made history by destroying the host nations Brazil, in Brazil's backyard 7 1, which will be remembered forever.
So while the German's had the luck on their side with how they had dismantled the Brazilians within 25 minutes in Rio, and had a days rest while Argentina played a day later for 130 minutes plus penalty's, this is still one of the most satisfying world cup victory's in world cup history for Germany, or for any other team who did this.