In general, mostly for single phase loading, Delta/Star Trafo using. And then impact for customers must be 1 Phase Hot Hot wire and back neutral. Not IT. TT or they TNC-S using.

Nobody good reason Delta Delta trafo for Onshore using.

Agree. Sometimes we need to wise in design in terms of application. We cannot put any good point in one hand. In ship application, I guess we need to maintain no backflow from hull except we have more than 1 ground fault and make close circuit. I like to said above because in mostly electrical wiring, delta delta system is not recommended because ground overvoltage uncontrolled, stress caused by unremoved faults, circulating current due to unbalance, etc. So mitigation is we require PIM or EFM and locator and also we required to design balance at each phase (consumers 1 phase).