Following the quantum supremacy controversy is very frustrating. It gets constantly framed as a decisive step that changes everything, which is wrong. But then there's also an opposite and equally wrong reaction that any challenges to the claim prove that quantum computing doesn't work at all.

The reality is that quantum computing technology has been improving at the same steady pace for decades, and quantum supremacy was recently invented as a concrete but not very useful goal that people could realistically aim for in the near term. That is a totally standard and legitimate way of guiding technological progress.

The problem is that quantum supremacy is vaguely defined (what does "infeasible on any classical computer" mean? what computers can you use, and for how long?) but it is presented to the public as a sharp boundary -- which means that every company in the field has a huge incentive to claim they are the first. This IBM claim is not a fundamental objection. Given that everything they say is correct, Google could still achieve quantum supremacy by their standards just by incremental improvement, slapping a few more qubits on. So why even bother disputing Google's claim? Because it will set them back a few years, and that's enough time for IBM to make a claim of its own. That's why academics, who have no stake in what company gets the hype, will just consider this whole episode rather distasteful.