What is a black hole site

Some sites seem biased not to post links on other sites, or if they post links, they're all nofollow. These sites are called "black holes," or "black hole," a metaphor that hints at cosmic objects whose attraction prevents them from escaping.

The most famous example of the first case is the New York Times, which places links only to its own articles. The second case illustrates Wikipedia offering an abundance of links, but all in nofollow.
We will discuss interest from the point of view of optimization, this practice.

1) Positive

is the effect ?

If we proceed from the sites in question, you might think that this is not harmful to them, but we need to take a closer look at them. NYT has great fame and is considered a reliable source of information, he theoretically does not need to quote sources, except when he talks about another site... This is a practice that interferes with the navigation of Internet users.
To access elements, a password is often required, engines cannot index it, so optimization is not their priority.

The Wikipedia case is also different, since, using the TrustRank factor (it is favored by engines) and FreshRank (constant content updates), it does not depend much on PageRank.
Using nofollow may be necessary on joint sites to prevent spam, and not on other sites.

2) Can it be recommended?

Google's algorithm is almost entirely based on links to assess the relevance and value of a page for a query. This is what made it successful and allowed it to remove the Altavista engine from the landscape. Without all these links, Google costs no more than Altavista .
If at the moment there is no visible penalty for positioning, especially on gullible sites, we can expect this to change.

3) Does it bring an advantage

?

The advantage of not linking to a page from another site is that the page has a link to its own. Crosswords, if they are most common, have no value.

In all other cases, external links enrich the content of the page and contribute to its selection for results, and choice is more important than positioning, content is more important than optimization .
Given that sometimes the results of pages compiled mainly from link lists come out on top, one can doubt the value of the black door policy. For example, an example of a Digg.com that depends only on external connections provided by depositors...

And then, except for the case of Wikipedia, to which beginners proudly put links at every opportunity, you should not expect webmasters to support the site that they see applying such a policy.
And Internet users value sites that force them to open the Web, such a site is also of less value.

• SoKwake. This extension in Firefox has the ability to show links that are nofollow on visited pages.
• NYT opens its content. I don't know if they have read my article;), but they have just decided (December 4, 2008) to open their content to externally sourced articles. Proof that a black site is not good
!