Every big company suffers from “not invented here” syndrome. It’s not always just because of arrogance. For example, as an engineer at Google, it can be less hassle to use a first-party library than a third-party one.

Also your list of examples is pretty bad. Guava is one I remember filling a real need when I worked at a small Java shop, and as I recall there was no widely used alternative to Protobuf when it came out. Gradle isn’t even from Google at all!