There's scale, and then there's _scale_. And I can happily believe that Twitter is working at the latter.
It's like something like AWS or Azure. You can provision and deploy a K8s cluster? Awesome! Now, can you do that consistently for the next 100 thousand K8s clusters you're selling to your clients?
I think regardless of scale, spending over a year working on edit functionality is endemic of something being horribly wrong organizationally. Maybe it doesn't even involve the software engineering groups (though it probably does). But that's simply not something that takes even a fraction of that time in a healthy organization.
It's like something like AWS or Azure. You can provision and deploy a K8s cluster? Awesome! Now, can you do that consistently for the next 100 thousand K8s clusters you're selling to your clients?
It's a very different kettle of fish.