I should’ve perhaps given more context about this – Snikket is a project aimed at packaging the Prosody XMPP server, and providing a more consistent user-facing experience. Part of this is in consolidating client efforts for various platform-specific clients under a single name (and in the future, UX). Currently, this means forks of Conversations for Android, and Siskin for iOS, which closely follow upstream with only light modifications.
XMPP was and remains a viable choice of protocol for personal chats (as opposed to IRC, which is mostly aimed at public group chats), and has improved in bounds since it was last popular (almost a decade ago). That said, XMPP has a marketing problem, and the XSF (the foundation that oversees the development of the protocol) has thus far stayed away from pushing for some sort of better, user-facing brand. Snikket is a project that tries to do just that, as a community-owned project.
I’m not directly involved with Snikket or the XMPP community, other than as a spectator, but moved my personal chats over to XMPP with a self-hosted instance of Prosody around a year ago, and have been very satisfied with how robust the system is (which, in part, is owed to how good Conversations is as a client, even on old hardware).