Since mover is about individual files rather than the whole array I would not consider it an ‘array level’ activity. That does not mean that there is not a case for having more visibility of when it is running.
As you say mover can affect performance and if you have the Parity Check Tuning plugin installed you can get ‘notice’ level notifications when mover starts and stops if it happens at the same time an array operation is running as these two types of operation interact badly from a performance perspective.
There is a trade-off around when to generate notifications. I think many people prefer to get none at all in normal daily running if everything is running smoothly, and only get informed about deviations from that.