The reason soccer at Euros is mediocre at best is simple: most of the teams adopted (consciously or sub-consciously) Barcelona’s (read: Guardiola’s) playing style: endless and nauseating passing back at the slightest pressure from the opposition. With Barca’s personnel (assembled at a great cost), “possession” style may be working, but not for any other team, national or club one.
This style is death to football as a spectacle -players are afraid to take chances on the field. France, in my opinion, does it less than the others, they have individually strong players willing to take risks.
That’s international soccer in a nutshell. Compare the quality of play in the Euros or World Cup to Champions League. It’s night and day. Players only have so much time to practice together for the National Team, and rosters constantly change.
It explains why teams like Iceland and Wales can have success in these tournaments. While they may not be nearly as talented, their rosters are more stable and the players are used to playing together.