The DMCA creates a liability shield for sites that accept uploads and creates a procedure for takedowns. But without the DMCA, the company's lawyers could still send a nasty letter to the web hosting site, and they'd be even more incentivized to prevent unreviewed uploads from users in the first place because they wouldn't have the liability shield.
Also, the takedown / liability shield parts of the DMCA are also only relevant when the people running the site are not the people who uploaded the content. If you want to host your own website and claim that you're republishing the manuals because of fair use, that part of the DMCA doesn't affect you at all.
(The DMCA does meaningfully interact with right-to-repair in its anti-circumvention provisions, though.)