It wouldn't be a good measure for Google.
Take my site for example...
No paid links,
99.99% pages validate.
No broken links [approx 500,000]
Authoritive and Government Inbound links.
My site is now PR3
Still no paid links, broken links etc.
The site hasn't altered or diverted from what it was when it was a PR6.
The site is still #1 or high up in the SERPS as before.
What has altered are the inbound links.
So, if a number of sites that were linking to me have decided to fold, then why should I be penalized by that ?
Sorry, your theory does not make any sense.