I fully agree with you that experience matters a lot in sports like football. Olympic Games show this where older players help younger ones. Real Madrid kept Luka Modric because he is valuable even if he is older. Experienced players like Modric and Cristiano Ronaldo lead and guide team when things get tough. They inspire younger players to keep going. When Ronaldo missed penalty he did not give up. He took next one with confidence showing his experience and strength. Experienced players help teams stay strong during difficult times and encourage their teammates to keep pushing forward. They are important for building strong team that can win.
Even though older players are needed because they have experience, there are also levels of weaknesses they have, such as fitness when playing the full 90 minutes. Luka Modric was not played for 90 minutes in a crucial match because Ancelotti realized that his physique was no longer the same.
Most coaches only play three older players during a game and the rest will be played by much easier players. In terms of experience and mentality, older players will be much better and they can help young players to develop.
However, if you face a team that has a defensive and attacking strategy, older players will have a little difficulty keeping up because they rely on running and physicality.