At the scale twitter exists right now it is anything but simple. Had it been built from scratch it could have run fine with its current staff.

But the current staff needs to maintain code from a MUCH larger staff. That's hard. Especially with microservices where every team did "their own thing" and some teams just vanished completely. You have "dark areas" where no one knows how stuff works and what's going on.

Normally when you downsize at this scale you do this in an orderly way. Every person hands off their work and responsibility. Spends a couple of weeks writing docs and instructions and then leaves. This was done quickly and violently. I'm sure there's many repercussions we don't see simply because the systems are simply running. Once the team looks at some containers and decides to pull the plug to "see what happens" we'll find out...