Comment by throwawayp123

Well, a physical open/close switch that's in line with the microphone lead would do the same thing. But, obviously that would be assuming privacy needs are incorporated into the design. I would imagine this could be added on some older laptop models with more physical space(I'm thinking of older thinkpads), but it would be a non-trivial process of opening a case, adding a cut-out for a switch, etc.