What is the purpose of modifying the example domain in data example?

I've been doing a lot of example domain edits recently. When using an example URL, the domain should be an approved example domain such as:

• example.com
• example.net
• mysite.example
• pageA.example

See these Wikipedia articles and RFCs that explain how the domains are reserved and approved for example usage:

• example.com - RFC 2606, section 3 and Wikipedia
• .example - RFC 2606, section 2 and Wikipedia

Using a real domain name is not desired because it can:

• Bestow unwarranted SEO benefit to the domain, especially when linked, but possibly even just through a mention.
• Cause problems for the domain when it gets unwanted requests from code that uses it as an example or when web crawlers find and hit the bogus URLs.

Stack Overflow actually prohibits new and edited posts from containing many incorrectly used example domains such as "mysite" or "domain" with a real top level domain suffix. I believe that this regular expression is in place that prevents a post from being submitted if the regular expression matches:

https?://(www\.)?(domain|xxx|xyz|abc|site|mysite|mydomain)\.(com|org|net)(?![a-z0-9\-]+|\.[a-z0-9]+)

To Henry Ecker's point, I have revamped my editing tool to prefer to use example.com over mysite.example if there is just one example domain used in the post. In the cases where two or more example domain are needed for comparison it often makes more sense to use the .example TLD like:

• siteA.example
• siteB.example

or

• myserver.example
• myhost.example
• mydns.example