Maybe I'm missing something but it seems like you wouldn't need an especially powerful quantum computer to do this.

Quantum computers have tons of uses. They're just not powerful enough for the more interesting problems yet.

Many of the hardest problems in computer science will become tractable with quantum computers of sufficient size.

Question: when the D-Wave was first announced, people were saying it wasn't a "real" quantum computer, but I can't remember why. Is that still the case for these models?

Lol, bullshit. Plenty easy to generate sufficiently random numbers for any purpose without these boondoggles.

Because it was a quantum annealing machine?

> quantum computers that exist today could produce random numbers that can't be faked

That’s a strange phrasing. What is a fake random number? Besides, random noise from the environment is not predictable to any extent that lets you break crypto.

> Many of the hardest problems in computer science will become tractable with quantum computers of sufficient size.

I would say some, not many. Many of the hardest problems are NP Complete, and quantum computers are not expected to help in solving those.

> Question: when the D-Wave was first announced, people were saying it wasn’t a “real” quantum computer, but I can’t remember why. Is that still the case for these models?

It’s not a general quantum computer, so you can’t put e.g. Shor’s algorithm on it.