[squaresmile]

Yes, it's one of the reason. As a result, it's super rare to refer to someone by their family name in Vietnamese. Casually people use given names and formally people use full names.

Family names usually come up when referring to the whole family branch of 9-10+ generations like the Nguyễn family or the Bùi family. Because there are few family names, you often see family branches use family name+middle name of the first ancestor to be more specific.