There are definitely cases where Wikipedia contributions have helped someone's academic career (like this one). However, I think it's exceedingly rare at major research universities.
Once you have tenure, it's worth looking into this. Then your department is already stuck with you, and they are likely to be somewhat more flexible in evaluation. For example, full professor promotions can be quite a bit less rigorous than tenure cases, and they are sometimes approached from a perspective of "Professor X has been a good departmental citizen and put in their time. We want them to be promoted to full professor eventually, so what basis can we find for justifying the promotion?" (This can happen even in departments that would never consider approaching a tenure decision that way. The big difference is that people who don't get tenure leave, while people who are stuck as associate professors may hang around the department feeling bitter for decades.) If you've done some unusual community service, then that might be when the university decides to recognize it.
However, I'd be wary of doing more than briefly mentioning Wikipedia before tenure. It's just not respected or valued by many professors, so the downside is greater than the upside. A lot of hiring isn't based on totaling up some sort of abstract value for the different parts of the application. Instead, it's based on an overall feeling you create of being a desirable colleague. If anyone rolls their eyes and wonders why you waste your time on something, then that will actually hurt your chances. If 20% of the department reacts this way, you've got a real problem.