The Scrum technique is applicable in any process that requires planning, but there're various cases where the team is continuously working on activities as and when required. A typical example of this use case is customer support projects, where a certain number of people are assigned to handle the issues that're raised for a particular product or project by the company. Usually, these support issues require an immediate response and detailed planning isn't required.
In such scenarios, the overall visualization of pending issues is important. A Kanban board doesn't have any plan mode like the Scrum board. It only has work mode, which is similar to a Scrum board.