Please don't take my question negatively. I acknowledge that not everything is about ROI.
For example I often let my team scratch their own itches by developing tools just for the sake of having fun and learning new toys. Perhaps this is the case with TaskTiger?
It is true that we've spent quite some time working on TaskTiger where we could've used an off-the-shelf task queue system. However, since we've created it, it allowed us to develop new features a lot faster and spend a lot less time debugging issues.
We were using Celery before and it was a big pain with memory leaks, periodic tasks not working as expected, some tasks being lost for no apparent reason, and poor visibility into both aggregate statistics and individual tasks. We spent too much time debugging Celery's issues instead of working on our core business. Here's some more context: https://github.com/closeio/tasktiger/issues/141#issuecomment...
Advanced features like scheduled tasks, unique queues, and task locks have helped us move faster, too.