I'm not really sure about the culture of English Wikipedia, but I'd try extrapolating the picture from my experience.

> My impression is that it's territorialism, where a few academic subject matter experts have gained enough reputation to control a page, and now won't let anyone edit it.

I guess it's mostly true. It's more likely to happen if the author has put extensive efforts on writing the article and has successfully defended one's article. But I'd give a minor correction: now they won't let anyone from whose writing style, don't appear to be a person who is familiar to Wikipedia and its cultural norm to edit it.

If you've edited enough Wikipedia articles and participated in the community long enough, you'll be trained to be extremely cautious. And it's very easy to tell from your writing style, mainly it's about (1) citing sources, and (2) neutral tone.

For example, if there is an article about cryptography, and there is an outdated mention of RC4. You may want to add more information, and write

> Nowadays, RC4 is insecure and considered unsuitable for secure applications, thus it is banned and rarely used.

To a Wikipedia editor like me, I'll read this sentence as,

> Nowadays [when?], RC4 is insecure [who says?] and considered unsuitable for secure applications [what applications?], thus it is banned [by whom?] and rarely used [for what?].

If I'm the editor, I'll first spending 30 minutes to find some sources to back the claims. Sometimes, the claims are so obvious that you'll need to be creative when finding sources, peer-reviewed papers and the introductory textbooks are often good sources. Then, I'll write,

> Since 2013, due to the discovery of additional weakness in RC4, such as [[BEAST attack]], or biases in the ciphertext stream[1], well-known cryptographers such as Matthew Green criticized its continued use despite questionable security status[2]. In 2015, the use of RC4 in SSL/TLS is prohibited by publication of RFC7465 standard[3].

[1] Pouyan Sepehrdad; Serge Vaudenay; Martin Vuagnoux (2011). Discovery and Exploitation of New Biases in RC4. Lecture Notes in Computer Science. 6544. pp. 74–91. doi:10.1007/978-3-642-19574-7_5

[2] Matthew Green. "Attack of the week: RC4 is kind of broken in TLS". Cryptography Engineering. (NOTE: this is a blogpost, and normally not a reliable source, it's best to find a news article from a news portal that quote M. Green indirectly).

[3] IETF. "RFC 7465 - Prohibiting RC4 Cipher Suites".

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See the differences?

> 1. Why the difference in cultures of deletion?

> 2. What are the implications?

Each version of Wikipedia operates independently (direct interventions from the Wikimedia Foundation exist, but rare), the rules of the English Wikipedia sometimes don't even applies. Thus, developing different culture in each community is not surprising.

In this case, I think it's simply a difference in philosophy, namely, whether we should take a more liberal approach or a more conservative approach on the enforcement of policies.

There are always enough articles on Wikipedia, and a lot of them do not even reach the common standard of Wikipedia, major reworks are always needed. For example, some articles are written like a personal essay, you can still find these articles on English Wikipedia, if the topics are not common to be reviewed by enough people. Original research is another major problem, some articles not only express opinions of other sources, but some of their own without citations. Meanwhile, the issue of Eternal September and the constant influx of below-average edits can only make the situation worse. In the extreme case, some believe the addition of a poorly-written article is worse than nothing.

Other people believe that we should tolerate the existence of below-average edits, and articles that don't strictly fit Wikipedia's standard of notability, have original researches, etc, to encourage contributions. If you see poorly-written content, it's best for someone who know better to fix it in the future.

Histrionically, members of the Chinese Wikipedia always believe the number of editors are not enough and the community should take an inclusionist idea and be relatively open to contributions. Even today, due to the Great Firewall, it's still a major opinion. But there's also a deletionist faction, concerning the quality of the articles. But it seems on Chinese Wikipedia, neither faction dominates, and for most of the time there is a somewhat peaceful coexistence.

For example, in comparison to lacking professional participants, Chinese Wikipedia seems to be more welcoming for edits on rock stars, video games, or animations. A lot of these articles contain fandom culture that is not really adheres to Wikipedia's policies. A few years ago, there was even a "Spoiler Warning!" templates, which is quite funny. Though standards have been higher in recently years, templates like these have already been canceled because it's unsuitable for an encyclopedia, but still, it's mainly inclusionism here...

Also, the enforcement of rules is more passive. If you add some paragraphs to an article that looks reasonable, most editors won't touch it, unless it's controversial.

On the other hand, if you ask for a peer-review, you'll encounter the faction of deletionism. The most common example is participating the community vote to decide whether a new article should be showed on the homepage (Do You Know..., a common way to increase exposure and feedback of new articles). It's likely that you'll face a conservative review.

I think this system, more or less, works. But the Chinese Wikipedia does have a lot of pooly-written articles, I have to say.