If there is a phsyical principle that stops QCs from working, then trying to build QCs is probably the best way to make progress in fundamental physics.

Yes, quantum computers are good physics research in the same way that ITER can be considered good plasma research. Neither will produce a working product that some people are expecting. I'm not sure that QC will discover the problem before we infer it theoretically due to the many engineering challenges, but it's possible. If any real progress is made in QC, my bet's on boson sampling.

Yeah, seems very win-win. Either we get a working quantum computer or we make revolutionary new discoveries in physics. Either option would be pretty exciting.

Isn't the paper mentioned in the article literally proving that wrong? Google managed to scale error correction and achieved less noisy qbits.

Sure, and analogously we're able to build bigger and more effective rockets than 50 years ago. We'll never travel faster than light though, because the speed of light is known to be the limit. I'm saying there will be some ultimate limit to coherence as well, but quantum mechanics is incomplete as a model of reality so we just don't see that in the math yet.

If that's the case, the QC computer endeavors are still worthwhile since while failing to scale them we may develop another piece of a more complete model of reality.

Could you briefly summarize one of the reasons you think QM is incomplete? I would agree with you that there is no reason to expect coherence to scale, but I don't know of any reason for it not to scale either.

Nobody knows of any certain reasons to not scale, but there's plenty of speculation. Someone else posted about Gil Kilai in this subthread, so he's one high profile person that has documented his skepticism on quantum computing and explained his reasons.

For my part, I don't think quantum foundations are on a firm footing. I think the measurement problem is still unresolved to a satisfactory degree, which means our understanding of decoherence is incomplete.

Per the link I posted above, there's also a good chance that gravity is inherently decoherent, which means entanglement will naturally breakdown in various conditions around mass.

I've also developed skepticism of quantum field theories. For one, the supposedly "most precise calculation in physics" has been marred by numerous mistakes and even fraud (electron magnetic moment). Renormalization is also sketchy business.

A more fringe reason, but one I think will resolve some of those issues is a growing skepticism of continuity [1], even for classical mechanics; continuous formalisms just seem to lead to logical and physical absurdities, like Norton's Dome and singularities in GR. Discrete theories are only now getting a little attention, but they're promising [2] because they seem to eliminate some of the formal structure (gauges), and the infinities disappear.

[1] https://arxiv.org/abs/1609.01421

[2] https://arxiv.org/abs/1902.08997