Comment by Izkata

I tried out like five or six of those back when they were trendy, and they all had one or more of these issues that made them unusable:

* Changes being tied to a commit (akin to git notes) so issues could have different status and comments on different branches. No overall view of the project.

* Using their own branches to separate from code state, which made a huge mess when looking at your branches or git history.

* Using a separate space (like git notes does, I forget what this is called), which isn't included in the standard push/pull.

* All of the above being distributed, issues in your checkout could be very different than someone else's, and now you have to merge those too.

* No non-developer UI for project managers to see or comment on issues.