Twitter had a lot of side projects and people that were not needed to run their core business. E.g. they used to have a Linux kernel engineering team [1]. They argued their value, but I was always a tad skeptical. Even if they earned their keep in terms of ROI, Twitter can definitely be run without kernel engineers.
Twitter used to have 7500 employees and now it is working perfectly ok with 1500~
What am I missing from business perspective?