Primary goal of Eclipse is to build a general purpose tool platform.
Writing software is hard – mostly because of all the people you have to talk to.
One of the biggest problem in developing software is integrating all the tools you have to use. Eclipse is trying to provide a universal tooling platform to enable all of the tools to talk to each other.
Eclipse is never done: there is always a new language to integrate, there is always a new platform to run on.
There are around 415 committers on various projects around Eclipse
The RCP platform was almost entirely community-driven.