I'm self taught programmer, I don't code professionally but feel confident that I can build any software related widget I ever dreamed up. That said, coding interview stuff I have seen is like gibberish and I don't see how it correlates to the day to day job of building software. Maybe some types of software (lower level systems stuff and such come to mind). It seems like everyone online discussing it feels about the same too. So honestly not sure if that's signal or noise for you, lol.