A non-general quantum computer could still be considered to be a "quantum computer" in the way that physicists use the term. We'd definitely consider a computer that could "only" run Shor's algorithm to be one, so that's not a reason to write off the D-Wave.
Being not-general-purpose means it's not a computer. If it's not a computer, it can't be a quantum computer.
As far as I can tell, D-wave's machines do appear to use quantum effects, but that doesn't make them quantum computers. They're quantum calculators.