It became a project kept alive primarily to demonstrate the Open Source model, and was no longer changing the world. And listen to your customers. Even though Mozilla code was constantly open and available, there was never a release. You can't go that long without calling something a release. People lose interest.
Developers begin to lose hope.
When someone is first beginning to contribute, they especially need to see some kind of payback, some kind of positive reinforcement, right away. For example, if someone were running a Web browser, then stopped, added a simple new command to the source, recompiled, and had that same Web browser plus their addition, they would be motivated to do this again, and possibly to tackle larger projects. We never got there. We never distributed the source code to a working Web browser, more importantly, to the Web browser that people were actually using. We didn't release the source code to the most-previous release of Netscape Navigator.