One of the things that I think is sad about the decimation of Twitter eng is that Twitter was doing a lot of interesting (and high ROI) eng work that, at younger companies, is mostly outsourced at great cost.

A few examples off the top of my head:

The now gutted HWENG group was so good at server design that, in a meeting with Intel, the Intel folks couldn't believe the power envelope Twitter achieved and Google thought we were lying about our costs during cloud price negotiations.