You mean a conspiracy theory about why. Though the article does not dispute that demographic changes are taking place, or even that they are the result of deliberate changes of immigration policy, it does go to great lengths to avoid mentioning them. This is not by accident - there is a lively debate on its talk page about including (more) demographic statistics*, to which the editors are highly resistant.
For example, there is not a single graph found in the entire article similar to that at the beginning of https://en.wikipedia.org/wiki/Immigration_to_France
Like refusing to mention JFK is dead on JFK assassination conspiracy articles.
*https://en.wikipedia.org/wiki/Talk:Great_Replacement#Lack_of... among others