Pretty simple, I think LDB has come to the point that we don't need to advertise display addons on the addon pages anymore. I think it's placing unnecessary bias on displays making it harder for new displays to come through, also keeping a list of updated displays on every addon page is somewhat taedious.
Yes. I suspect that's where most people get the LDB display. They install. Wonder why it doesn't "show up". Go complain on the comments. Random person answers: "You need an LDB Display. I use Foo." User downloads Foo.
I'm not sure I would just leave it at "Use a display addon." Maybe a page on the wowace wiki or wowwiki that has the master list of LDB providers and the corresponding link to the author's preferred release site?
That way the author/helpful poster can just paste the URL to the wiki page url into their description/comment and hey-presto no unintentional display advertising.