at no point did I suggest we should not believe someone when they say their name. But what purpose is a complete unit in a name if it is what 1/2 of everyone el

at no point did I suggest we should not believe someone when they say their name. But what purpose is a complete unit in a name if it is what 1/2 of everyone else in a country has too? the icelandic case is different, as it does after all function as a lastname, just a suffix on the lastname. I see no value in this, its kinda like putting salutation into the name. I would receive NO value in having an additional firstname of "Mr"