Sometimes I wonder if the main use of quantum computers will just be to verifiably have no side channels, because any such side channel would act as a measureme

Sometimes I wonder if the main use of quantum computers will just be to verifiably have no side channels, because any such side channel would act as a measurement (which produces phase errors that you can check for). It wouldn't be efficient but the computation would be provably isolated from the rest of the universe. Well... other than the input at the start and the output at the end.