You make the statement, “When a telephone, camcorder, and tape recorder are separate devices, three total microphones are needed. When they all collapse into a smartphone, only one microphone is necessary.” While this may be factual, it is deceiving. Not everyone had a telephone, a camcorder or a tape recorder. Everyone now has a smartphone, even peoples living in the Kalahari Desert and the Amazon jungle. Though the data may be hard to mine, I think you will find there are millions of more microphones now than ever before. Also, people discard smartphones now annually were with a telephone, they were generally kept for years. Same with camcorders and tape recorder.