yeah, i dislike the decline of forums as a medium as well. the discord-ification of the internet has been a frustrating descent into madness and it leads to information scarcity.
discord tried doing a forums feature so servers could be front-facing and indexable but it never really went anywhere.
a quick rundown of what happened with social groups can be found with these posts: https://forums.terraria.org/index.php?threads/what-if-there-was-%E2%80%9Cclubs%E2%80%9D-or-something-for-tcf-users-to-join.140956/#post-3246005 | https://forums.terraria.org/index.php?threads/what-if-there-was-%E2%80%9Cclubs%E2%80%9D-or-something-for-tcf-users-to-join.140956/#post-3246295
the thread about the change to private messages/conversations can be found here as well: https://forums.terraria.org/index.php?threads/announcement-regarding-changes-to-conversations-private-messages.133894/