The most obvious legal defense for publishers is that when we buy games digitally these days, we're actually buying a conditional license to play the game—with the main condition being that the license can be revoked for any reason. Steam's subscriber agreement is explicit about this, saying that the games we buy "are licensed, not sold."
But if put in front of judges, those agreements won't necessarily hold up in every country, argues Scott. It'd be hard to get a favorable judgment in the US, but the hope of the campaign is that if one country, such as France, decides that publishers have to find a way to keep their games playable indefinitely, the industry will adopt new practices globally.
I found a YouTube link in your comment. Here are links to the same video on alternative frontends that protect your privacy: