I think the mentality behind that is it would be too easy to manipulate. People could just buy expired domains and redirect them to their website. I am going through a similar issue with a website.
I would put your old website through Moz's opensite explorer and identify the backlinks. Then I would reach out to all the domains that linked to your old website and ask them to update the link.
Also, did you do a domain level redirect or redirect each individual page?
That should help you out some.