Scars can be hugely important and detrimental to a human body's optimal function long after the event that creates them. Through creating adhesions and other alterations during the healing process (for instance, if the scar goes keloid), disruption can occur in our connective tissues' ability to transmit tension and other signals.
Think of a scar as a hole cut in a flat sheet, then tied in a rough knot. When you pull on one corner of this sheet, the pull is no longer smooth across it as before the hole had been cut and tied. There is now bunching up and slack and tautness in places.
Working on a scar to release adhesions and restore function can be very important to a human body, no matter how old the scar can be or where it is located.