By such a definition any tradition related to gender would be sexist. The tradition is that the wife will change her name. This tradition is why it makes up the majority of cases.
You can do hyphenated last names for a kid and let the kids decide what names they want to carry forward for the next generation. Or they can make up their own. The point is it’s up to them and they can choose whatever they want and not be coerced to do something because of some tradition that is rooted in sexism.