It's just a cultural thing, like many Europeans have names like Magnus
Magnus*son*, and innumerable similar Slavic suffices.

Slavic? I thought it came from the Icelandic. There surnames come from the
first name of the parent.
So Magnusson is the male offspring of a chap whose first name was Magnus
something elseson. If he also had a female offspring her surname would be
Magnusdottir. (Magnus’s daughter)

It made for an interesting telephone book....