D-Wave is not a universal quantum computer. It’s a quantum annealer [0].

[0] https://www.quora.com/Why-is-D-Waves-quantum-computer-not-co...

There is no known reason why it is theoretically impossible.

However, despite many people claiming otherwise, there are currently no situations (other than contrived benchmarks) where a quantum computer is better than a digital computer.

Of course it is! But, can it catch up to the 60-year head start that classical computing enjoys? That remains to be seen.