It's a rubbish set-up. Klaus noted that it's to stop tactical fouling, but when we go into the QF with up to 40 players in danger of missing the semi-final should their team go through and they get a yellow card, there's something off.
3 yellow cards earning a suspension for semis would have been better, with the tally re-setting in the semi, so only red-carded scoundrels miss the final. Imagine if this nonsense deprived UEFA a Bale, Ozil or Ronaldo in the final. Hisense and Hyundai would not be pleased.