There are certainly possible reasons why quantum computing could be impossible. To me the most compelling of these would be that the error rate of physical qubi

There are certainly possible reasons why quantum computing could be impossible. To me the most compelling of these would be that the error rate of physical qubits might fundamentally always exceed the threshold for correction with any real ECC as the number of logical qubits increases. I highly recommend reading [1] for an overview of the various skeptical viewpoints on quantum computing. Note that, while Aaronson argues most of the initial arguments are trivially wrong, he admits that whether or not error correction is fundamentally impossible is an open question. [1] https://www.scottaaronson.com/democritus/lec14.html https://www.scottaaronson.com/democritus/lec14.html