I see point (2) very often combined with a higer-up also bypassing hierachy. I even get the feeling that the higher-ups feel like they are helping because they are so hands-on.

What happens in every case is that the priority of that task for the assignee is the highest. Sometimes this is a help, because often people have to multitask a lot of tasks with the same priority.

But in even more cases it might be a huge distraction.