Does buying Domains help SEO

Does buying multiple domains help improve search engine rankings? Link building being a major step in SEO companies and optimizers have sort after purchasing multiple domains to increase their rankings. Using this strategy they tend to quickly increase quality links from .org, .net and other domains useful for ranking.

However, claims are that “Google resets all backward links to a site once it knows that the domain has been expired or reset.”

Now, how about if the site expires when no one is aware or it happens accidentally? What if the domain is transfered? We do not have much information about this. However, Matt does mention not to register unrelated domains in an attempt to get those pre-existing links to your account.