If you consider people born in 1927 (the inventor of the system) to be generation Z, then yes.
Hegel (b. 1770) is purported to have used a version of Zettelkasten, as described by Hegel's sister: "He approached his reading as follows: Everything that seemed remarkable to him he wrote on a separate sheet of paper, which he identified at the top by a general label under which the particular content had to be subsumed. In the center of the upper edge he then wrote in large letters—not infrequently using Fraktur letters—the keyword of the article. These pages he ordered alphabetically ... and thus could by means of this simple method use his excerpts at any moment. "
In a tech sense, yes, it's nothing more than a wiki. The difference lies in the usage: wikis tend to organize their content using encyclopedic categories and hierarchies. A Zettelkasten is supposed to be much more goal-oriented, so that the right notes are found and interacted with depending on our work.
Why is it for generation Z?
Cuz as a millenial I've been using tomboy / gnote as a personal wiki long before 'zettlekassen' showed up on HN, and I know a few others who run more online wikis.
...but zettelkasten is a concept that's hundreds of years old, so it seems strange to assign it to a young generation. I think it would be more accurate to say that personal wikis are the millenials' zettelkasten.
I'm doing so because the trend of calling your notes by a old german word seems to be the new innovation here.