A quantum question that is "interesting" would also be similar to finding order out of disorder (e.g. factoring).
Like I can model shooting a cannon ball out of a cannon and it will tell me where it lands. Or I can model a cannon ball sitting on the ground and it will tell me where the cannon was?
However, the current consensus take of quantum uncertainty means _if_ such a simulator exists, it cannot be of our universe. Or, more likely, such a perfect simulator does not exist.
Of course all of this is about a hypothetical of a hypothetical at this point...
(This is the same problem as entropy (our current understanding of it). We know it is increasing one-way w.r.t. time, and we can imagine what it means to "reverse entropy" and that there's nothing really theoretically preventing that, but we can't build an actual machine to do that.)
They don't seem worried about this though, since at least research-wise just working with quantum as a new tool to solve problems itself is intellectually interesting (and the "solves classically challenging problems" is a good way to frame the work's potential impact to general audiences). Also, there's other supposed uses of quantum beyond just computing, like for communication etc.
Are we talking complexity classes here, or just "problems we've found hard in practice, but that which may in fact be in P even if P != NP"?
Like I would've thought that solving BQP problems like integer factorization would be the criterion (since they're proven to be faster under QC assuming P != NP etc.). But that's evidently the researchers aren't holding themselves up to that standard, so what bar are they using exactly? Are they just going with some sort of "if it walks like a duck then it's a duck" criterion, or are they using problems that they can formally prove lack efficient classical solutions under a well-regarded hypothesis like P != NP?