User:Cambalachero/Verifiability does not guarantee inclusion

All the information included in articles in Wikipedia must be verifiable, that is, it must be available in Reliable sources. However, verifiability is necessary but not sufficient, and some content may not be included in a given article, even if it is verifiable.

Trivia
An article about a given topic in Wikipedia will talk about the most important and defining aspects of it. For example, an article about a person will have the biography of that person. But Wikipedia does not include everything about the topic. That a musician released a new album is noteworthy info, that he helped an elder woman cross the street is not.

Excessive in-story content
Wikipedia includes articles about works of fiction, and those articles have a section that explains the plot of the work of fiction. Those sections usually don't cite references: it is assumed that the work of fiction is itself the reference. Then we can explain the plot in full detail, scene by scene and focusing even on the portraits on the walls, right? No. Wikipedia aims for an out-of-universe perspective. Plots are described in summary, to explain the basic idea of what is the work about, and no more. Wikipedia is more interested in the real-world context of the work: how was it made, other works that influenced the authors, the reception it had with both critics and public; that kind of stuff.

Undue weight
Although articles must mention all relevant viewpoints, it is possible to influence the reader towards a certain one by adding extra information to make it seem more credible, or less. Information added with such a purpose is usually removed.

Content is elsewhere in the article
A common misunderstanding that may take place is when someone finds a certain information and feels that the Wikipedia article should mention it, failing to realize that some previous editor already thought of that and already added that information. Although it is not required to read the full article before editing it, it may be a good idea to check it first, in special the sections where that info should be expected to be. But even if someone already mentioned the info, it may be still be possible to work upon it: rewrite it if needed for better clarity or make it MOS-complaint, add extra info that was not present in the first text, add references if the text lacks them or we have better ones, etc.

The lead section is a special case, as it is meant to be a summary of the whole article, and it is the most visible part of it. Certain information may be included in a later section, and be implied in the lead. For example, "he won several awards" in the lead, and a detailed list of such awards in a dedicated section. Adding the detailed information in the lead, such as one specific award, should only be done when it is more noteworthy than the others (for example, a Nobel Prize would likely merit a specific mention), or when it is an intrinsic part of the subject's notability.

Content is in a sub-article
Wikipedia has articles about many topics, but the amount of things that may be said about them is not always the same. For example, a single article about a rock band should probably be enough, but Rock music is a topic of a much bigger scope. In those cases, articles move info to related articles: subgenres, regional scenes, subculture, etc). It may be tempting to mention something or someone at the parent article, but if the article on Rock Music listed every Rock band ever, its article size would grow so big it would be almost impossible to maintain, much less to actually read.