I think this is a great idea in principle. Being able to learn and understand the solution quickly on the internet is a very valuable skill.

At the same time, there is deeper stuff that really isn't suited to this approach. If I were conducting an interview, I'd set the candidate a task the evening before their interview that involved something I knew they had know experience in, to see how well they can delve into and understand new tools.

A face to face interview is a great way to really understand how good a candidate's core knowledge is. Do they understand data structures and how to manipulate them? Do they understand algorithms and their complexity? Sure, you can look this stuff up, but it's the kind of knowledge you need to have before you even start.