Is the incentive even necessary? It would be worth testing if there are enough scientists who are keen to promote information sharing in their field without some minimal reward
I also wonder if this will make the penalties for uploaders more severe since it becomes a commercial act
It's not clear whether this is even using a privacy-oriented cryptocurrency arrangement (assuming that would actually be private). What this appears to be presenting is a system where users will be pay, and be paid, to violate copyright, in a way that may well be easily traceable and linkable to real identities, and, for US users, likely even needs to be reported on tax returns even when just paying. The 'cup of coffee' statement entirely misses the point: the nature of the process changes when payments are involved.
Added to that are statements saying that they have systems to remove watermarks and protect the identity of users. If they're envisioning this being something researchers and students contribute to, that watermark removal system is likely to fail on many occasions, and people are potentially going to get themselves severely hurt.
I often feel like academic publishing and paper availability is somewhat of a cold war between researchers and publishers, where researchers practically need to violate copyright to research effectively, while publishers can't pursue those violations too severely, or they risk researchers ostracizing them, so we end up with unspoken understandings of acceptable violations. But a system like goes entirely outside of acceptable boundaries.
If a publisher came to a university and said, hey, this researcher put up the final copy of their own paper on their personal website in violation of copyright, the university might tell the researcher to replace the copy with a manuscript one. If a publisher comes to a university (or the police) and says they can show concrete evidence that one of their students is being paid through a foreign criminal organization to knowingly violate the terms of the university's subscriptions and likely criminally violate copyright, it seems like it could have a very different outcome.
A decade ago the publishing system harassed a researcher because he was downloading too many papers, going after him for millions in copyright "damages," only stopping proceedings after he ended his own life.
And that's the risk here, in part: this system allows the practice to be presented as a paid criminal enterprise, and allows individual users to be presented as criminal participants.