Stripe CTF had a time limit and required very specific solutions. Figuring out the answers on an IQ test often involves creative problem solving. I don't see a difference except in an individual's preconceived notions about the significance of the test itself.
Yes, but the Stripe CTF isn't going to compare you to the entire body of humanity: just to the already-brilliant people who want to take a crack at it. I didn't know about the challenge, but I'd consider if I failed at it, that I don't have sufficient knowledge in a certain technology area, not that my ability to abstract and reason is measured to a global degree.
