I think Wikipedia references are encouraged to use archive links because it will show the page at the time that they used it as a reference as opposed to linking to the live page which can change at any time.
Wikipedia references should include both the live url and the archive url, and then set the “dead” flag to either true or false to choose which url to link to. Probably either an automated process or an inattentive user falsely marked the url as dead.
Wikipedia has been around long enough that many of the citation links pointing to other websites are broken. So there are several wiki bots that go around replacing direct links with links to the archived pages.
