Workflow builder: can't multi-select and move several nodes together on the canvas

Summary

The builder canvas only lets you move one node at a time. There's no way to select several nodes (rubber-band drag or shift-click) and move them together, which makes re-laying-out anything beyond a trivial workflow tedious.

Expected

Rubber-band and shift-click multi-select, and drag the selection as a group. (Bonus: multi-delete of the selection.)