Bit of a sensational title? This doesn't "break WiFi encryption", only device isolation if the attacker is already in the same network.
Many businesses and universities, and likely some government offices, rely on client isolation for segmenting their networks. It’s a big deal.
I'm a co-author on the paper: I would personally not use the word break but instead bypass, to indeed clarify we can't just 'break' any network. We specifically target client isolation, which is nowadays often used, and that proved possible to bypass. If you don't rely on client/network isolation, you are safe.