Care to shed more light on your intuitions? I get that the engineering challenges are hard (or we'd have figured it out by now). And everyone seems pretty bad

Care to shed more light on your intuitions? I get that the engineering challenges are hard (or we'd have figured it out by now). And everyone seems pretty bad at predicting how long it will take for us to build something fundamentally new. But from the physical impossibility side, what would have to be true/what would we learn if we discovered that physical reality _doesn't_ support quantum computation with a large number of qubits and sufficient accuracy? I did do a course which included some quantum computation material and the professor highlighted that it wasn't actually demonstrated whether nature would be so "extravagant" ... but I haven't heard anyone describe what the universe would need to be like to both support the quantum phenomena that we've already studied and demonstrated, but to disallow some larger/more complex arrangements of what seem to be the same principles.