For one it would stop sanctioned ships dead cold. As it is russian lawyers are playing EU like a fiddle with nonsense arguments https://www.dailyfinland.fi/europe/46719/Sanctioned-Russian-...

"The Federal Fiscal Court (BFH) said there was "reasonable doubt as to the legality of the confiscation measures," as it was unclear whether the ship had had authorization to enter and leave the EU despite the sanctions, due to an exemption applicable in emergencies."