Well, from a personal point of view, when we did the reddit hiring, it really annoyed us when someone posted their solution to one of the problems, because there were clearly people who were copying the solution to get their cover letter to us. So then we had to read those letter to determine that no, this person isn't actually qualified, and now we wasted our time (and theirs).

So that is where I was saying the harm comes from. It's not hugely threatening, it's just annoying.

That just means that posting public problem to hire people isn't a good idea.

Don't you think that's throwing the baby out with the bath water a little bit?

I agree that it's a problem that people can easily dupe an interview by copying a readymade result, but that doesn't imply that public problems are unilaterally a bad idea.

In fact, I'd liken this to a public announcement of a security exploit. Someone has found an insecurity within the social algorithm of public problem interviews.

To me, there is little correlation between a good hire and someone who solved a public challenge. What does it prove?

Your original claim was that one bad anecdote at reddit was enough evidence to consider "that posting public problem to hire people isn't a good idea."

Do you think that all public interviewing options are unilaterally unable to defend against people divulging public problems?

A public problem is essentially just a contest. Lots of contests are considered good figures of merit. If you win a nobel prize or a fields medal, that's a sort of public problem solving exercise. Would you hire someone who won a nobel prize over someone else, all other things being equal? I certainly would.

Maybe the real issue here is that these interview problems aren't sufficiently challenging or interesting such that the barrier to entry is keeping answer-copiers out.

Unless you're Gregori Perelman, for example, you're likely not going to be taken seriously or given much credit for solving the Poincaré conjecture.

PS. I don't think it was fair to downvote me just because I disagree with the pov. Is that why I was downvoted?

I have extensive recruitment experience and I understand the idea of "let's filter out as much as we can to gain time".

My experience is: it doesn't work, you will have to crawl through resumes, do phone interview and have people come over. You can be clever about what you ask in a resume and how you do your interviews but you will somehow need a list of skills and experience and somehow you will have to talk to the people you want to hire.

Additionally, you don't want people who just "find solutions to problems", you probably want people who build systems. That's a different skill set, which is why you will not filter out the right type with a teaser.

You will also unreliably assess their skills because you cannot tell how much time it took or if they actually did it.

Have people come over. Evaluate their technical and human skill. Nothing fancy, just straightforward stuff.

If in one day of interview you think they're people you'd like to work with, hire them. If you have any doubt, don't.

Let go the idea of the exam. You're a company not an university.

The sad part is that most people who see this are also able to pass such test.