"Some candidates asked for an interview without completing the exercise. Unfortunately, this was not an option, as this would not be fair for the candidates who worked hard to get to the interview."
This is just how I look at it, but if I reply to a company about a position, I'd like to know about the position before you make me jump through hoops. The exercise itself is okay, and a brief test like this is much, much better than making a candidate fill out an assessment, but why would I invest that kind of time if I don't even know whether or not I want the job. Think about it from the candidate's perspective, some people in this thread note having done 10s/100s of interviews. Imagine how much time they would spend doing menial coding exercises before even getting to know about the actual position other than the JD.
Again, its probably just me, but last year I literally thanked companies for their time because I didn't know anything about the job and their company and they were already asking me to do take home assignments. Sorry but I have a life, and critically to anyone who's hiring; plenty of people reaching out to me not trying to make me jump through hoops. Maybe if you invited more than 24 people for the exercise or just spoke to some people first, you would've gotten a better pool of (potential) candidates.