So it's not so much the OLD sites that get listed, but the INNOVATORS. That is, the ones that don't "target overcrowded niches" but create new ones (that is, force us to build new categories). And it's not the NEW sites that tend not to get listed, but the IMITATORS.
Perhaps true of sites that innovated 3 years ago. Sites that innovate today, will show up in dmoz 3 years from now.
You can put a cute spin on it, and claim that any website created after 2002 is probably a rip off of some earlier concept. If it offers you some comfort, I have no objection.
It is still a good reason for search engines not to rely on ODP data.
But that you so obsessively don't like it -- I can't think of any reason that is not iscreditable ... to you.
Conversely, I could say that your "obsessive" love and defense of the ODP is a discredit to you, if I ran out of cogent arguments and was left with nothing but ad hominem attacks. I would not, however, because that would be a discredit to me.