The main issue in implementing such a system is testing and certification. If you use quizzes then there is nothing to stop the student from looking up the answers in another window. The system can still be made but the tests need to be designed so that students can't just look up the answers. The solution is applied knowledge problems.

For example instead of asking someone about the physical properties of a metal you would ask them what metal they would use for a certain construction and why. Student programmers would be required to write short scripts. Student geographers would interpret maps. Student lawyers could say how a client should behave is different situations.

Basically you would test whether people can use their knowledge instead of whether they can communicate it to avoid students second-hand communication. The downside is that questions are harder to make.