I do think the label applies to researchers. And except for the case of "tracking down citations to webpages that don't exist anymore," researchers can continue to do all those things using traditional methods (which may be a harder, but still easy enough, especially if it's your job).
It's also the case that pre-web, a lot of that sort of content was pretty much lost to time. Per a discussion, a little while back, relatively little from the BBS era is preserved because it was mostly a distributed group of hobbyists.
No they can't. Citations that point to URL's that no longer exist require IA. There's no other tool currently.
Or any other authority figure. My favorite exchange that I personally witnessed during early COVID was this one:
A, conspiratorially: You should hear what the dentist has to say about the COVID vaccine.
B: Why, does it affect my teeth?
[0] an informative article and the American College of Dentists response:
https://www.theatlantic.com/magazine/archive/2019/05/the-tro...
https://www.acd.org/position-papers/the-college-responds-to-...
It's pretty much indispensible to anybody who's a researcher.
It's very frequent that you're tracking down citations to webpages that don't exist anymore, and the IA is the only way to find sources.
Not to mention that it's also often the only way to quickly get access to non-bestseller books that are more than a couple of decades old, which is also commonly needed for research purposes. Many of these books are only otherwise available in the country's largest research libraries. (Google has copies too, but nobody can view them.)
It's not weird or a subculture unless you think those labels apply to researchers. And there are a lot of researchers out there, across academics, non-fiction authors, and journalists.