It's incredibly frustrating that a resource that holds so much unique content and history decided that the hill it was going to die on was content that is readily available elsewhere.

The content wasn't "readily available".

People were either locked at home, the libraries were closed, or else disease-ridden.

Archive.org was providing knowledge in a time of emergency when people had no other means of access to knowledge, and people who may have been out of work due to a pandemic, and thus unable to afford to buy the stuff if it even was available via mail.

It wasn't some trivial lark.

I'm just not convinced that what they provided couldn'tve been provided just as well by proper pirate sites, or that they are more discoverable than pirate sites.

Not aware of that. Could you elaborate?

From my understanding, in reaction to libraries being closed everywhere due to the 'rona, they started to "give away" ebooks, which the copyright holders were Not Happy with.