I have no idea where the idea that having someone come on site for 6+ hours wasting a dozen peoples time became the norm as opposed to talking to someone for 1 or 2 hours and truly speaking with them to understand what they know.
You're completely right, if you can't talk shop and not know when someone is bullshitting you shouldn't be the one interviewing.
How would this even fly in other industries? Are you telling me that someone can bluff their way discussing the intricacies of surgery to other surgeons without looking like a moron? Or discussing particle physics with a researcher and stand on equal footing? I honestly want to hear a conversation where a liar with no programming skills is able to convince a Senior level Software Engineer that they are on equal skill sets.
The best interview experience I had, where I eventually worked for the company, was having an hour conversation with the Engineering Manager who I would be working under then being ask basic programming Qs based on our conversation we had. Everyone in the company was interviewed the same way. IMO the resulting team was very professional and skilled on various levels from various backgrounds. I actually felt like a human at that job and not a person hired because of x thing.
I'll never forget I had an interview where they asked me a question about finding anagrams. At that moment in my life, I've never heard of an anagram or knew what it was. The Interviewer then explaining what it was to me made me feel very humiliated. I completely bombed every question because I had the audacity to not know about this thing where the interviewers knew about thing therefore I should know thing as well. I immediately understood how cultural biases can effect candidates getting jobs. I can only imagine how worst it is for people not from traditional backgrounds in this industry.
None of the techniques discussed in this article are even attempting to judge productivity, they are attempts to judge coding ability. It's good that you bring up productivity though; that's what we are really after, isn't it?
>from a short conversation
I'd argue 30 minutes to an hour is not a short conversation. Do you think an imposter could fool you about tech (assuming you are an active programmer) for 30 minutes to an hour?
>it's probably better to see the proof
You're not proving anything except the fact that the candidate has memorized a merge sort algorithm (or whatever trivia you are testing for). What you really want to know is, can they ship?
I think you should at least consider the idea that not only are these tests and homework assignments (past fizz buzz) a poor indicator of ability, they active repel any candidate good enough to be in even reasonable demand. I mean you have a lot of people on not only this thread, but many other threads saying the same thing.
Time for a little reflection, what does your company offer that even a mediocre developer can't get in 20 other places in your city? I mean if I could get "market rates," and a "fine cubicle," and "standard PTO" in 20 places, tell me again why I would bother with this rigamarole?