Most Famous brands and leaders in their field have many.
Who should you copy?
Books.com | Mortgage.com | Hotels.com | ...
An Authoritative address carry competitive advantages: Credibility and Trust.
Overshadow An authority website will overshadow some of the the others in the same field.
OvershadowPart 2 Overshadow from your biggest competitors is reduced. Example: Insurance.com would be less affected by the leader's names.
Bypass means that visitors aware of this website will bypass the search engines.
Reduces the competition Visitors bypassing search engines, bypass competitor's Ads.
Save on Advertising. (1) As much traffic for less. (2) Free traffic: The traffic coming back to a site you own: you don't pay for that traffic anymore.
Who is doing it?
Sample
Here is a sample of a few leaders and the additional websites they own.