[ig1]

They're a necessity. For the simple reason that too many people lie on their CV, no matter how good their CV looks you have no-idea how much of it is accurate.

Obviously there are cases where you wouldn't use it, but generally they only apply when you know someone's capable of coding anyway (i.e. due to an indisputable reputation, experience working with them, etc.).

However as a predictive measure it's fairly limited in that it's a binary indicator. If someone fails then there's a fair chance they're a terrible developer, if someone passes there's a fair chance they're not a terrible developer.