Can't reply to the child comment -- but worth pointing out that open sourcing your growth magic would be considered pretty dumb by most/all of SV. In fact open sourcing your scaling magic is considered dumb by most of SV. Finally, Twitter clearly doesn't have growth magic (or they'd be growing faster) -- but is that an engineer's fault? At the end of the day, any user facing engineering is beholden to the product team. Engineers at Twitter can run experiments, but they can't get those experiments shipped unless a PM is behind it. I'm not saying the PM team at Twitter are blocking awesome ideas -- just that there's a real shortage of awesome ideas that have been proven to work in the Twitter context. It's tough.

[full disclosure, I wrote one of the projects mentioned above.]

I'm not saying it is easy or disparaging the work of the engineers there. I am saying it seems like they have a different approach to how tech fits in with the goals of the company. To oversimplify, Twitter is focused on efficiency while others are focused on growth. Maybe the actual goals are different, but that is the impression I get looking at their output.