We may distinguish between USENET the public network that is part of the Internet (considerd "out of date" by many because it is not Web based, and indeed suffering from spam) and the USENET protocol, which you can use to set up your private version of USENET-like discussion groups.

In fact, many organizations had (and some still may have) inhouse groups, often prefixed "local." e.g. "local.events", "local.jokes" etc.

Advantage: threaded discussions, open standard (many existing open source readers e.g. Emacs: M-x gnus)