Nobody said that this is a perfect system. Only that it is a better system. Do you refuse to lock your car door because anyone could just break the window. Security isn't about absolutes. It is about increasingly making it more difficult for an attacker to compromise you.
This system is simple enough that it could get a mass market uptake. That would vastly increase the security for a large number of people. For simple sites like Slashdot it would eliminate identifiable information stored in their database. As an example of the increased security, NeoGaf a popular gaming site, right now is forcing a password reset due to their system being compromised. If they had been using SQRL then that would be unnecessary.
This also provides built in onetime password protection. Compared to the current username/password security method this is far and away better, and will be relatively easy to set up.