It’s a necessity as most countries leagues will have been done for 2-3 weeks when the tournament gets underway. The Premier League, La Liga, Bundesliga and Serie A all end this weekend, the Portugal Primeira finishes tonight, the Eredivisie is in the midst of the playoffs for both Europe and promotion/relegation
It's been one of the most condensed, cramped seasons in history. The lads need a break before a major tournament not more pointless friendlies.