remember that not everything is precious and needs to be reserved.
(a) The "We're deleting all your content" message was only visible on group home pages, not when viewing messages, meaning a lot of the people who used the web-interface didn't know about the shutdown.
(b) The email sent out to all members about the deletion was sent weeks after the initial notice, often didn't arrive, and was inaccurate (dates had changed by the time people received the email). So many folks that used the email interface also didn't know about the deletion.
(c) The amount of time given was far too short. Yahoo Groups had existed as a brand since January 2001, and was based off Yahoo Clubs / eGroups, both of which had existed for several years before that. Two months notice for a 20+ year old service is laughable.
(c) The site has been unreliable during the last few months, due to the high traffic of people trying to save their stuff. This has significantly complicated efforts to archive it.
(d) Yahoo's solution to the data destruction, their "Get My Data" feature, is poorly thought out and often doesn't work. No photos are included in the download unless uploaded by that account. Many groups had members who uploaded photos / scans / schematics / etc.. and since left the group. Those photos are now lost. We've also found the downloads to be missing content that necessitated the request be made multiple times until you could patch together a complete version from all the incomplete ones.
And that's Yahoo's decision to make?
(I fully suppose maliciousness, but there might be plausible non-malicious justifications.)
Yahoo had a nice interface to allow everyone that was a member of any group to download everything for their personal and private use, and it worked fine. Random external parties republishing other people's old posts though is not OK at all and is a massive breech of privacy, and is a violation.
Because of the threat that one's opinions may be archived and forevermore propagated by random third parties, at this point in history one would have to be insane to express a genuine opinion publicly. Therefore these efforts have a chilling effect on free speech and are inimical to democracy.
Consent is paramount to privacy, and archiving everything without consent is a breaking a huge privacy and trust boundary.
This is data going back decades, there has to be someone in power somewhere on that team that realizes the value of this data? We're not asking them to keep it up, just to make it easy to archive.