Everything previous I'm aware of has been multicast based or address based, like email or mailing lists.As others remarked, IRC is follower-based. You follow a bunch of channels by sending subscription message (JOIN #channel-name) to central authority (IRC server). The server keeps track of who follows which channel, and brokers any PRIVMSG #channel message messages to the followers, until the person does PART #channel-name or disconnects. Aside of that, a direct person-to-person mechanism exists just as well, also via the PRIVMSG command.
The USER nickname command provides, among other, list of (public) channels the named person follows, which some IRC clients use to allow user to follow the same channels.
Yes, there is a difference between an IRC channel and a singular persona, but it is not as clear-cut as it may seem on its face. On one hand, some channels are muted, and only admins, or just a single admin, can post. On the other, Twitter handles often stand for multiple persons, speaking for one organization, team etc.
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As an IRC user, I am ashamed and appalled of how low our industry has fallen -- somebody applies for a patent for what (after cursory read seems to me) a copy of well-known and long-established functionality.