Why am I not surprised here?
I’ve been warning folks against Yahoo groups for this very reason. Same with google groups.
Everything can be gone in an instant, and there is nothing you can do about it.
And we will repeat again, as the vast majority of Yahoo groups have migrated to Groups.io, yet another private entity that will probably be sold and allowed to stagnate. Rinse and repeat.
A commenter on Fedi noted that he has posts from 20 years ago still available on Usenet, but recent posts on discord and phpbb web forums etc, long gone as the
individual websites and software have deteriorated, been pwned, or abandoned.
The thing is Yahoo groups, Groups.io, etc are just glorified mailing lists with additional services like file storage, wikis, etc. Could Netnews/Mailing-lists along with DAT/Bittorrent/IPFS/Datashards like file storage and websites provide a federated long-term replacement not dependent on individual corporations.
Understandably, even Usenet would be gone without entities providing infrastucture, but that seems to outlasted most web forums and Yahoo/Google groups even considering the wasteland that is Usenet currently.