Lynx (Battery) grounding for off-grid marine system

Dear collegues,
Pls share you knowledge and experience for young boat builders =)
I prepare to create victron system (off grid quattro + transformer) and i have a question about grounding\ protect system.

 In the Victron book p 7.7 on the diagram it is shown common grounding point for all mines battery. What is good or bad about this grounding? (For example, will the ship rast due to such grounding? (steel hull)). Why this system is not realized on many many boats? 

Thanks a lot!

https://www.victronenergy.com/media/pg/The_Wiring_Unlimited_book/en/ground,-earth-and-electrical-safety.html