Reading between the lines, you seem upset about having to answer questions about technical problems you perceive to be irrelevant, and that these technical problems are more likely to be solved successfully by those who have recently practiced them (e.g. graduates).
I too agree that, while abstract technical interview questions have little bearing on most day-to-day work, they do some things quite well:
1 - Define a well-bounded problem of sufficient difficulty 2 - Give the interviewee a good baseline for objective success 3 - Exercise a person's mind to think about complicated problems
While they are contrived and not entirely representative of daily work, they are not without value.