Here are some common reasons developers don't work on servers:
- They are already working on a project in Graal, so they can't pick up anything else major.
- They don't care about Graal enough to dedicate their time to it.
- They don't like Graal at all.
Making a fun little script or helping on the forums is miles and miles away from the amount of work it takes to get anything done on a server. Most people realize that, so they generally don't even bother making commitments and failing to meet them.