If I link activities in a Gantt chart to show dependencies, the reason is clear. I can see how they relate to each other and if the predecessor slips, so does the successor.
In Jira I can say B is blocked by A. but so what? Other than saying that - which doesn't even seem to manifest on the task board - why would I do that? They don't really seem to move together nor would it be obvious to a stakeholder looking at the board that they are in any way connected.
