I qualified that statement with on purpose for a reason. The "thief" is doing exactly what the owner intended with their property.

If companies put coupon codes in the public domain (internet) with the foreknowledge and knowing intention that they will be distributed beyond the "intended" group I have great difficulty classifying it as theft - after all, people are merely doing what the originators intended. In the case of coupon codes they retain the right to deny usage and charge the "offender" the correct fee at any moment normally, at least read the T&C's

I suppose next people will give lectures about overweight and oversize luggage - that too is "theft"