Except when the candidate isn't told that they will have a timed coding interview in advance and in general what it would be.

I've been asked to write a full-stack app from scratch, and I spent like half of the time debugging the webpack config, which could've easily been solved by having a template prepared in advance if I knew what I was doing.

If anyone's reading these, please have the coders work off of an already existing template that you give them.