> The decision was made to go with Eclipse. Then it magically went into some sort of internal box/decision process, and came out IntelliJ instead. I've always thought this was because of a sufficiently highly placed Android person with a personal preference, but I could be 100% wrong.

I'm relying purely on memory, but all of the reasons were super public at the time. The internal Java editor tooling team decided that they weren't investing any more time into Intellij. And then a few months later, the Android team relaunched Android Studio using Intellij with full internal support. The existing Java tooling squad put up some amount of fuss saying that they had already made the decision, and the Android team gave a long and diplomatic response that could be compressed down into, "we don't report to you and we don't care what you think." This coincided with the entirety of Google becoming mobile native, so the mobile team were given free rein to call the shots.

> IMO IntelliJ never worked very well in google3

YMMV, we had some people in Docs/Drive who invested a lot of time into making Intellij usable for everyone, and following their system, it worked way better for us than Eclipse did. All of the "Let me sing you the song of my people ::UI freezes::" memes were very true in my experience.