…with a few obvious exceptions such as libellous pages. If Wikipedia's mission is collecting the world's knowledge and history, they should keep everything. The deletion practices were made in the early 2000s, a time where Wikipedia barely had enough funding to survive. Now, Wikipedia's host organization is swimming scuba-diving in money, so there is no economic burden to keeping all articles.
Not only does keeping all articles make Wikipedia more useful to everyone, but also encourages more authors to contribute, since they don't have the uncertainty whether their article will be kept.
Since keeping all articles makes Wikipedia more useful to readers, it increases donations that offset any cost that would come from it.
If the Wayback Machine can retain half a trillion pages, Wikipedia sure as hell could be able to do 1% of that.
A quote from a long-term administrator:
Deleting an article that other people have worked on is objectively worse than keeping it and letting people find out about the topic. No-one’s even asking for it to be promoted or featured or anything. By all means slap a notice on it telling readers that it’s “sourced entirely to blogs and fandom wikis”. I have never heard any good reason from anyone why any good-faith contribution to Wikipedia (that isn’t vandalism, libel, or just garbage) needs to be deleted. All that serves to do is give a massive middle finger to anyone trying to give something to the world, and produces an inferior encyclopedia with less coverage. — Timwi (talk) 20:11, 30 January 2022 (UTC)
Originally posted to /r/PopularOpinion, but just like many subreddits, their filter is bogus garbage.