But that only helps you. That doesn't help anyone else who needs that old reference. Saving things in a way that those backups can be shared and distributed,

But that only helps you. That doesn't help anyone else who needs that old reference. Saving things in a way that those backups can be shared and distributed, like WARC files donated to the Internet Archive, can help ensure that when your hard disk crashes and your backups fail and you lose those PDFs, the things you wanted to save will still be out there.