Their traffic is potential donations

Something tells me a person is way less likely to donate if they're consuming the content through an LLM middleman

I don't know -- as I said in another comment, my Wikipedia usage has gone down 90% thanks to LLMs.

But that means I'm still using it. Especially for more reference stuff like lists of episodes, filmographies, etc. As well as equations, math techniques, etc.

If you're the kind of person who donates to Wikipedia, you're probably still using it some even if less, and continue to recognize its importance. Possibly even more, as a kind of collaboratively-edited authority like Wikipedia only becomes more important as AI "slop" becomes more prevalent across blogs etc.

But were you originally convinced to donate by one of those giant Jimmy Wales banners that come up once a year? People won't see them anymore if they're using AI summaries.

In terms of the effectiveness of the banner, yes it absolutely does. Multiple exposures increase your propensity to convert.