An argument I've heard is that since hydration breaks can affect the game, if you are going to have them they should be mandatory and at the same time in all games in a tournament rather than doing them like they did when they were originally introduced in 2014. Then they were only done in games when the conditions on the field got dangerous.
football games can have "momentum". An extra break allows for a breather and a tactical intervention from the coach. That also why we saw keepers sitting down (faking injury) in the Premier league last season.
Anyway, a hydration break while it's raining is a bit of a tell it has nothing to do with the needs of the players.
