Aye, indeed. Many fan projects have ended like that. It's not completely their fault, though. Sometimes IRL stuff really pulls you away from your personal projects, and sometimes you lose interest in ponies until some periods. Other than that, there are still many reasons.
First, they're not organised. The fandom is strong. We have someone in any proficiency we need to finish a project. Artist? We have hundreds. Writer? Even more, but only few are 'actually' writers. Musician? Good number. Programmer? Of course. What's the problem then? Organisation. People want to make names for themselves. They want to be the leader, or at least a big part of a project so they can be famous. That's why they start their own projects instead of joining the already existing ones. New projects, more things to be done, etc.
These new projects also weaken the already existing ones. They suck potential human resource which may be needed by the projects in progress. Not to mention that these leader-wanna-be aren't always professional. They just want to be the initiator, not actually the leader.
I've seen a project which simply gathered a bunch of people and the leader just asked the team to make something. The team members didn't know what to do, of course. I wouldn't blame them. All they knew was, "I'm an artist, and the project needs an artist, so I will join to help." The leader's excuse was funny. He said that the people who joined the team were supposed to know what they're going to do, so he didn't need to direct the team. Then why the hell did they need a leader?! He just waited for the team to finish the product so he could get fame for it. Blast it! Of course those artists, programmers, etc knew how to do their stuff, but they weren't leaders. They needed direction, and this focken arse hole, who claimed himself a leader, didn't do his job.
Unprofessional wanna-be. They kill.