What is the purpose of a reveal tie when using independent scaffold?

A reveal tie connects a scaffold to a building or structure that it is next to, usually the structure that is being worked on. Tying the scaffold to a structure increases its stability.

This is a quote from Wikipedia on reveal ties:

The least 'invasive' tie is a reveal tie. These use an opening in the structure but use a tube wedged horizontally in the opening. The reveal tube is usually held in place by a reveal screw pin (an adjustable threaded bar) and protective packing at either end. A transom tie tube links the reveal tube to the scaffold. Reveal ties are not well regarded, they rely solely on friction and need regular checking so it is not recommended that more than half of all ties be reveal ties.