interesting conclusion there, what makes you lean that way?
I suspect ranking 'degrades' slightly over time - don't keep adding content and lose places in the SERP.
Having said that, it's pretty much hypothetical. A ten year old domain will have more links and more content, and I think _that_ is why old domains rank well. It usually takes time to develop a great quantity of useful, ranking content and links, hence the perception that "aged domains" are more valuable.
Anyone else have thoughts / different view on this?
But yeah, old domains basically have had more time to accumulate trust/links/shares/content, so they're more likely to do better in the search engines.