Before Arch that role belonged to Gentoo.
To add, before the change the Gentoo wiki was a top resource when it came to Linux questions. Even if you didn’t use Gentoo you could find detailed information on how various parts of Linux worked.
One day the Gentoo wiki died. It got temporary mirrors quickly, but it took a long time to get up and working again. This left a huge opening for another wiki, the Arch wiki, to become the new top resource.
I suspect, for a number of reasons, Arch was always going to replace Gentoo as the “True Linux Explorer”, but the wiki outage accelerated it.
Reddit sorta half did it with the “other discussions” or duplicate tab.
As an example,
https://old.reddit.com/r/news/duplicates/1lvi6kb/a_clicktocancel_rule_intended_to_make_cancelling/
I never saw any apps implement it, but it does look like it was part of the API, but maybe it wasn’t robust enough.
I also know at one point, and possibly still, is that it lacked URL normalization. So for example, exanple.com/headline and example.com/headline#topstory would be treated as two different articles.
Similarly https://youtube.com/watch?v=dQw4w9WgXcQ and https://youtu.be/dQw4w9WgXcQ
Would be treated as separate articles.
These are all fixable problems, but require work.