I am very unsurprised by this outcome.
People wonder why good software becomes bad, and it’s because the people who were good at engineering are often outmaneuvered by corporate-politics savvy people in a growing company. One of the best political moves in a company is to have a lot of people under you.
A couple years ago, an engineer I know who has always been a very poor performer and lacks initiative, but is friendly and non-confrontational, was hired by GitHub. It would not have been hard for GitHub to find a much better engineer, but this person would be an easy person to keep under a manager on a team who wouldn’t leave or make waves. That can be more important to some managers than skills.