Yet another reason to buy stuff on GOG.
I'm from Brazil, so even though a clause like that is forbidden by law here, it's not like I can sue them anyway. Surely sucks for US/EU users, though.
They already do it with Origin and every recent game with online components.
I think this violates EU law anyway, so the EU agreement would not have the clause in it to begin with.
It's a shitty, anti-consumer line to draw in the sand (just because others have done it doesn't make it right), and hopefully we don't see Steam going farther down this rabbit hole of bad policies.