I could've written this exact post myself as I'm going through the process right now. So thank you for taking time to share and building the hound! Kudos.

As for the presently en Vogue hiring process for senior tech roles, I'd put a deserved blame on companies like Google, where this bookish and silly way of hiring was first codified by the founders and early employees who were fresh grads/drop outs from schools - and that's all they knew about how to judge who's better in class. And as more and more of people who went through that process leave and start their own companies, they follow the same process - thinking that's the best of breed way to hire.

As for age discrimination - it's very much alive and well - specifically in the SF Bay area. Which is a shame.