In fact, Scott Adams proposed this in The Dilbert Future as a workplace scheme to improve productivity (he called it 'OA5'). He may be accurate in thinking it's up to the employer to destigmatise leaving 'early' (when in fact it's a symptom of an employee having a good work-life balance, providing his performance is sufficient).
However, I've been thinking about this recently - the logical extreme is that you should never expect the employee to turn up at work at all, provided he performs his tasks (say via telecommuting). Perhaps employers mandate 'desk time' because it's important to have regular physical access to the employee, for example in order to talk to him? I can think of HR/legal reasons where a private in-person interview is needed in order to inform the employee of something or to retrieve information from him. Consequently, if an employee only came in to work for these meetings, it would be obvious when the employee was engaged in some sort of 'serious' communication with the company. It would make mass layoffs especially conspicuous and difficult for the company to hide.
However, I've been thinking about this recently - the logical extreme is that you should never expect the employee to turn up at work at all, provided he performs his tasks (say via telecommuting). Perhaps employers mandate 'desk time' because it's important to have regular physical access to the employee, for example in order to talk to him? I can think of HR/legal reasons where a private in-person interview is needed in order to inform the employee of something or to retrieve information from him. Consequently, if an employee only came in to work for these meetings, it would be obvious when the employee was engaged in some sort of 'serious' communication with the company. It would make mass layoffs especially conspicuous and difficult for the company to hide.