I think you have to factor in that South American sides are so awkward to play against as well and play like it's the 1980s and the referees allow it. The Copa America probably has more strength in depth now than even the Euros and the top teams are as strong. To win this competition Argentina would have had to get past Uruguay and Paraguay, Colombia and probably Brazil and Chile. Whoever wins the Euros next year will have an easier path. Although Chile have been very lucky with their draw.
Messi's winning the MOTM awards in this tournament so he's still the stand out performer. Argentina just aren't putting the ball in the net enough and Messi needs to be more prolific but he's putting them on a plate for players who can't finish.
Perhaps, but i recon that the top teams in Europe are at a higher level than the teams in South-America. It has been that way for a while.