What's to stop a more established site from ripping the content and using it's link pop to push out the new guy (just because a site is established does NOT mean they are ethical)?
More often than not, editorial catches these shady sites that are established (since there are so few out there that don't already have editorial actions).
That's the problem, a webmaster doesn't know the domain has a tarnished image when registering until it's too late.
That's why a webmaster searches for the domain name he wants to purchase in any/all engines he can think of before buying.
And besides, why buy a domain that has previously been owned? Most would agree that starting up a new, fresh name/site is much better than running with a name/site that already existed. Remember : they sold (or let the domain expire) for a reason.