Tracking dependent relationships between Issues and whether something is blocking another piece of work is important with any project process because it creates a central hub where everyone can communicate what’s needed without relying solely on meetings or comments to uncover important connections.

Blockers would give better insight into when an issue can be started,

bugzilla has had the concept of one or more ticket(s) blocking another for quite some time. We used that for over ten years before switching to GitLab and it is a feature I miss. A dependency tree between issues enables planning and workflow. This is can be seen as related to issues boards in that blocked issues should not be able to move ahead until the blockers are at least implemented perhaps reviewed.

It would be useful filter to have, also it would be useful to sort issues using topological order on Board and other issue listings, so the unblocked issues would be first.