Recruiting is a hard problem in itself. It seems like these methods are no longer a good solution to the problem. These interviewing methods at MS and other similar companies are more like a tradition, a process among so many other bureaucratic steps to get things done or drag things to completion.

They haven't evolved, and they are easily hackable. Spend some time researching on the internet and you will run into all questions you will be asked. The Same set of questions, reverse string at Microsoft, design parking lot at amazon, binary search tree problem at Google etc no originality from the interviewers, not all of course.

Some guy wrote a set of reference questions to ask in phone interviews 10 years back when he was at Amazon and even today people ask those exact 5 questions for phone interviews. It is so sick, the last time a guy asked me these, I felt sorry for myself, I called him a tool and I am now in process of bootstrapping.