FizzBuzz style questions are really important (eg. create an array with 4 numbers: 1, 2, 3 and 4 and output the values. Oh a "Java and Python 'expert'?". Please in both languages then!). Although I agree that home tasks and trick-algorithm questions are useless.
I don't think home tasks are useless, but they have to used properly. A home task geared to 1-2 hours seems reasonable for an exercise between the first and second interview. Some may say they'll just look up the answer (it's encouraged!), and that's why during the second interview the employer should discuss their answer. If the candidate can explain why they made particular decisions on the take home piece and have an intelligent discussion about the trade offs they took then who cares if they looked up the answer. In fact, the home test is probably closer to real programming since I don't know anyone who codes without Google nearby.
So, my preferred method is to use FizzBuzz as a first cut on the first interview and then give a take home quiz that should take the candidate 1-2 hours or less if they are good.
I see where you're coming from. I think the issue is that 99% (100%?) of all HNers would likely be great hires for most companies, so they see these questions as trivial, dumb, and not representative. Just the fact that someone thinks about these types of questions and reads programming blogs probably puts them ahead of most of the programming population.
The problem is that many of us have really never seen the mythical horrible programmer. The person that really can't even start a solution to FizzBuzz. The one that leaves the interviewer wondering how the person got jobs at other companies. I have seen and interviewed them before and it's frightening and uncomfortable for everyone involved. I've had candidates break down crying when I asked them to write a simple sql select statement on the board because their resume said expert in sql. For many, it's hard to fathom these people are out there, but they do exist.