Because France are another team which have a really strong defense line. As for Argentina defense they have no other choice than being extra careful here. Because even playing with 5 defenders might not be a certain solution.
There is no doubt that the Argentine coach will stick to the basic tactics of football. In the match against Croatia, he played in a formation of 4-4-2.
It would be great if he could try a 4-3-3 formation with either a central defensive midfielder or a central attacking midfielder against France.
Against France, I think the three-midfield formation might be a smart idea. There is no doubt that France have a very competent midfield and the Argentine players will have a hard time getting past them.
Overall, I think that all the coaches will give their utmost effort in order to give themselves the maximum chance of winning the trophy.