The bulk of the article is true. But companies are not lying when they say that legal risk is a reason not to send feedback.
Triplebyte is in the unusual position of being able to say, "Everyone who has enough technical skill gets through the interview." And that fact is sufficient to defuse their risk. But real companies don't have the luxury of ignoring non-technical aspects of the job.
Here are real reasons why I've seen people denied a job. "Nobody could understand his accent." "Accidental personal referenced summed him up as, 'Loves to make things crash and burn in production to see the pretty fireworks.'" "Nobody could believe the argument he got into at lunch."
In my books those are all valid reasons to not want to work with someone. However the first opens you up for an accusation of racism, the second would break a personal confidence, and the third had demonstrated sufficient irrationality that tiptoeing away was a great idea.
And you can't give feedback on technical issues, and not on the rest, because that amounts to a tacit acknowledgement that there was something non-technical. Leave the non-technical to your imagination and guess what happens?