How do you ask others for link opportunities? Most of the time people are only interested in either reciprocal links, or them providing guest posts on my site (when I reach out). And I can’t imagine if I did a round up post getting many inbound links. People would be thrilled that they had received a link, and wouldn’t create a reciprocal link to destroy the value.
When would this be useful? If your site has a blog with public commenting turned on, links within those comments could pass your reputation to pages that you may not be comfortable vouching for. Blog comment areas on pages are highly susceptible to comment spam. Nofollowing these user-added links ensures that you're not giving your page's hard-earned reputation to a spammy site.
For example, if a swimming pool business is trying to rank for "fiberglass pools" -- which is receiving 110,000 searches per month -- this short-tail keyword can be the one that represents the overarching topic on which they want to create content. The business would then identify a series of long-tail keywords that relate to this short-tail keyword, have reasonable monthly search volume, and help to elaborate on the topic of fiberglass pools. We'll talk more about these long-tails in the next step of this process.
The leading search engines, such as Google, Bing and Yahoo!, use crawlers to find pages for their algorithmic search results. Pages that are linked from other search engine indexed pages do not need to be submitted because they are found automatically. The Yahoo! Directory and DMOZ, two major directories which closed in 2014 and 2017 respectively, both required manual submission and human editorial review.[40] Google offers Google Search Console, for which an XML Sitemap feed can be created and submitted for free to ensure that all pages are found, especially pages that are not discoverable by automatically following links[41] in addition to their URL submission console.[42] Yahoo! formerly operated a paid submission service that guaranteed crawling for a cost per click;[43] however, this practice was discontinued in 2009.