It's all about scale IMO. If you're a massive company getting thousands of applicants, you simply need to weed out some of them with a basic test.

Personally, I hate "leet-code" style interview questions and nebulously defined take-home tasks.

The best interview questions I've had to answer are where you are given a series of contrived issues on an imaginary system which you have to diagnose and fix. It opens up the room for discussion and it's much closer to reality than fizz-buzz.