Companies already are doing what they say they are doing, even if it's unenforceable. The profit from doing so is more than the liabilities from any lawsuit might be receiving.
History shows that creating more legalese text won't add any more teeth. A specific example is how 90% of websites[1] are in violation[2] of the GDPR already.
The manifesto raises a good point about data not protected by copyright; but one can argue that models created from copyrighted content, what most artists I see are complaining about, are already in violation of copyright due to being derivative works (IANAL), yet already-existing copyright laws aren't helping[3].
So they way I understand this manifesto is, they are not adding anything new for copyrighted works (AFAIK, IANAL), but they are taking away rights from public domain works (let's see how that plays out with Disney, for example).
Hopefully this additional context clarifies where I'm coming from.
[1]: I'm making up that number but I'm probably lowballing it anyway.
[2]: Example: https://pkg.go.dev
[3]: But I bet if someone made a model from TV shows, now suddenly the already-existing copyright law would magically work for those specific cases. So basically, these randos without power are making a law that will only be enforced by those with power.
