The most thorough explanation of what "#thep0rtals" really are:
https://tilde.camp/openbook/IMPORTANT.txt
This is one of the earliest videos introducing #thep0rtals:
https://www.youtube.com/watch?v=6-j4FKongnE
"#thep0rtals" are essentially referring to a network of Openbook websites. There are supposed to be many different Openbook websites, each with their own purpose or collective identity, but all of them allow anyone to post anonymously. Although Openbook is just a website software, and not a decentralized software, the idea was that the website could still be decentralized just by having lots of different people putting up an instance of Openbook on their own servers, so that the website has lots of duplicates that all link to each other. This means, even if any of these websites go down for some reason, there will always be this whole network of nearly identical websites that allow people to continue communicating anonymously. The network of Openbook instances which all link to each other, altogether, is called #thep0rtals. Although a single p0rtal may go down, the idea is that with enough p0rtals the knowledgebase of #thep0rtals and all it's intelligent hashtags and their wiki definitions can persist across many websites so that #thep0rtals can continue to support an ongoing global communications that can never be destroyed.
This concept is especially important for people who are not as tech savvy, who still want to experience anonymity, and don't know how to use the Tor network and find IRC channels and all that crap.