Wilburforce - 5:05 pm on Oct 3, 2012 (gmt 0)
there are plenty of people who achieve good rankings without any artificial means and regularly survive Google updates
Including me, until Penguin. Penguin has identified and penalised two key terms on my site, one of which had ONLY unsolicited backlinks using the page subject as anchor text, and the other of which appears to have been the subject of succesful negative SEO.
I am certain - the threads on WebmasterWorld alone are pretty good evidence - there are plenty of people who achieved good rankings without any artificial means and who did not survive Penguin.
Similarly, there are plenty of people who achieved good rankings using artificial means and who did survive Penguin.
I don't think Google owe me anything, but that doesn't make Penguin a Good Thing, either generally or in its stated objective.
Having successfully used organic SERPS results as my primary marketing for new business from 2002 to 2012, my present view is that - even if current loss of ranking can be reversed - it has now become too unreliable to fulfil that role.
It doesn't really matter what Google's motives are or whether that outcome was intentional, but the fact is that good SEO today can be penalised tomorrow.