Quantum supremacy was mainly coined as a milestone as a response to certain vocal famous people (almost none physicists, which was the problem) who have been sk

Quantum supremacy was mainly coined as a milestone as a response to certain vocal famous people (almost none physicists, which was the problem) who have been skeptical about quantum computers at a fundamental level. That is to say, there is something in the nature which will always forbid the quantum speed up (as in the case of perpetual motion machines) however you design a quantum computer. Those certain individuals have publicly kept debating against it for years, from basically claiming that quantum computation is snake oil to moderate skeptical positions and kept saying either quantum computers can't do anything beyond the capabilities of classical computers (in terms of complexity) or that it's outright impossible to build one. For decades. (Some of those ramblings have appeared on news outlets and here as well as top news.) Physicists of course know that quantum speed up is real (which is why Feynman proposed it, and why there are so many working on this, and so much money is being poured into it) and that it is an "engineering" problem (albeit a very non-trivial one in uncharted waters) to build a device which can make use of it. Such experiments, although not of any practical use for people, are important to establish certain fundamental facts about nature in a way everyone (including people from other disciplines) can understand without studying quantum mechanics and the physics of the devices.