Argentina are a good team but they’re not as fluent.
Most talented is not the winner every time. Croatia went to the final of World Cup with an average team. Brazil may be the most valuable squad among all Copa America teams but that doesn't make them the automatic winner.
I have seen all four quarter finals and in my opinion Argentina played the best football among all 4 teams that reached semis. Argentina squad isn't perfect at all, they lack the required co-ordination, their talisman isn't in his best form but most importantly of all, they have required passion to win the cup. They look like completely different in quarterfinal in contrast to group stages. So sometimes passion plays upper-hand as compared to skills and can create wonders. I do believe we will see same teams in finals for thrice in a row but final outcome could be different this time.