I agree with the argument that most of the players will be in their late 20s or 30s. But in the previous editions, most of the European teams had good players in their early 20s. However this time (Qatar 2022) only a few of the European teams had such players. Some of the teams do have players who are 20 or 21 years old, but they are no match for the more experienced players. Players of the calibre of Erling Håland or Ronaldo of 2006 are extremely rare nowadays. Let's take the example of Germany. They have a few - Karim Adeyemi, Youssoufa Moukoko and Lukas Nmecha. But these players are not even regulars in the playing XI. Most of the attack is being done by Müller, Gnabry and Gündoğan.
That's why all teams have coaches who decide if experienced players should play or younger players. But when you look at the game against Japan that Germany lost, their worst players were Musiala who is 19 years old and Havertz who is 23 (I still count him as a young player). Maybe they would have won the game if their coach put more experienced players into the game from the start. Who knows. But every coach must think about introducing young players and that's best done by combining few young players with experienced players. If they keep playing with experienced players, the time will come when those players won't be competitive anymore and those younger players won't have experience in playing important games.