Something like the casinos–casinos site wouldn’t be listed because it doesn’t have original content. Compare that to this site. Night and day. The casinos–casinos site mostly gathers together information that is available on the casino sites themselves. That might be useful to surfers, but its just a copy to dmoz, since they list the casinos themselves.
The way to get a site similar to that listed would be to right real, genuine, in-depth reviews of each casino, not lists of features or copying the casino promo text, but first hand reviews. Dmoz doesn’t list online casino directory-type sites, but they do have a specific category for reviews where jacknoir and fairbet and others are listed.
There is no category for “portals”. You either need gambling game strategy content (the gambling category is under “games” after all), or reviews or original news content.
One thing you can see on resource-zone is over time they really cut back everywhere on directory type sites. They don’t want to list sites that link TO other sites, they want to list sites that get linked FROM other sites, if you get what I mean.