If players are unable to play players more than once in a day. Managers in the countries that play first would be forced to either not play the player and hope they sell. Or Play the player and possible not get a sale because some managers are only looking for players to fill in minutes. The point is that it would put those managers in the earlier timezones in a different, and arguable disadvantageous position in comparison to the later time zones, and will unlikely be an implemented change.