I've worked with OKR's at large e-commerce companies, small tech incubators, consultancy firms and "Unicorn" stage startups. At each stop OKR's were absolutely worthless.

What I really appreciate in reading this article is that they were absolutely worthless for the reasons this author has stated: there was no real empowerment behind them. Most often they were used for personal development since I had no meaningful say in my actual work. It's always a stretch to put personal development in terms of OKR's: "I'll write two blog posts this quarter." "I'll run one lunch and learn"-- ok those are fine activities but we hardly need OKR's to grow as engineers-- and just imagine how annoying it is to be at quarter's end struggling to write a blog post when you find out midway that you're enjoying learning in an entirely different manner.