Many countries simply don't care about imprinting their official narrative on Wikipedia.

Not on Wikipedia sure, but they do with many different type of media or local ways which is then translated into the "international news" (with a big sprinkle on top of non-sense and unqualified opinion).

On the contrary, injecting your own views/propaganda in Wikipedia is a great way for your content or your version of history to be included in the outputs of LLMs since they all rely more or less on it during their training phase.