You can argue legal merits all day but the reality is the little guy doesn't have much chance against FAANG lawyers without a lot of financial backing from elsewhere

All of the FAANG companies have railed against the overreach of DCMA Takedown Notices. However, they are bound by law to comply with them.

No they are not. They are required to comply or take on liability.

That is part of the rules required of distribution sites like YouTube, Apple Music, Spotify, etc., as defined in US law as part of the Digital Millennium Copyright Act (DCMA). Hence the name "DCMA Takedown Notice".