Those companies aren't hiring, they are just sifting market for rock starts. I have seen this in numerous places already — when a company has enough product leaders, but still enough money/time to hire a couple more, they begin whiteboarding people. Several years later those product owners will leave, and suddenly the interviews are reduced to "you worked with <insert technology name>? Know what <insert technical term> is? Accepte^W erm, I mean we will contact you tomorrow!"

Several weeks after passing the interview you start asking colleagues about their own interviews. And everyone has wastly different experience. Some were hired after being harrassed for hours. Others got job thanks to friendly tip...