Probably.
That's the problem with gigantic addons that try to include every feature you can imagine. Over time, they just get too big. It gets to be a lot of work to keep up with just bugfixing, let alone adding new features. Nobody actually uses every feature, so the features the developers don't use get neglected. Maybe the guy who handled feature X quit WoW, so he's not around anymore, and nobody else really has time to learn his code and take over properly, so that gets neglected. Before you know it, it's so full of bugs that you don't even know where to start.
Also, addon authors are just people. Life situations change. New jobs, new relationships, new family members, or new hobbies might mean they don't have as much time to play WoW and write addons anymore.
Or, they might just have gotten bored of WoW and quit.
