I absolutely agree. I did the same for the last couple of jobs I was invited for an interview. However, I think this only works because we're in the comfortable situation that there are more jobs than good developers.
Developers are definitely fortunate with the job market being the way it is. Even if that wasn't the case though, it is in the best interest of a company to create interviews where preparation isn't necessary. They want to measure the skills that a candidate has accrued over their career, not what they managed to cram in 2 weeks.
Someone brought up that new developers can't possibly do this. I agree mostly, but I think companies can still do something with the interview process here. You want new developers to have a strong thirst for learning. I once interviewed a bootcamp graduate who described an assignment where she refused to use a front end framework because she wanted to experience what it was like without one. Then she would know the full benefits the framework gave her.
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