Researching social movements — where relevant information is often on social media, or the websites of NGOs, universities, or corporations that reorganize them frequently — link rot is an acute problem. Increasingly, the default way to let a reader see the source you’re referencing is to provide an internet hyperlink, and yet there is no assurance that a link on a site which you don’t control will continue to work.
Jonathan Zittrain has an instructive article in The Atlantic about many of the dimensions of the problem. Strikingly, he cites a study by Kendra Albert and Larry Lessig that half the links cited in court opinions since 1996 no longer work, along with 75% of the links in the Harvard Law Review.
Beyond the Wayback Machine, which I already use extensively both to find material which is no longer online and to preserve links to live content that may be useful in the future, Zittrain suggests several other initiatives to help with the problem, including Perma and Robustify.