There is one key requirement of a mobile phone that doesn’t apply to a desktop scenario: the device MUST adhere to carrier-specific requirements, some of which

There is one key requirement of a mobile phone that doesn’t apply to a desktop scenario: the device MUST adhere to carrier-specific requirements, some of which may block access to telephony-associated hardware, or require that a manufacturer be able to provide a minimum standard of performance. Do you see AT&T, Verizon, T-Mobile or other carriers complaining about having only one browser engine per device?