I think it is some deffernce in knife fighting since some age.
I don't know when.There are many techincal revolutions like Spyderco;one-hand-open,pocket clip and light hundle,popularize of linear look let us one hand close,hard hundle of Titan,G10,and Alminium,and Xydex sheath in fixed blade,or Tanto blade.
I can't say carrent knives and old town knives are on same dimention to fight.
Before Spyderco,the only one-hand-open-close folder had been the Batafly,as now we have no need for batafly knife.In some old way,in city figthing,they used sharp thin blade automatic knife as Itarian stiletto.But now,it is old and so weak.
Carrent tactical knife can chop as full-tang fixed blade knife,we should use other method.
The Fairbirn=Sycks(I don't know how to spell) style dagger had been best to fight,but now it is so weak to think over the body armer.
And now,tanto blade and some new style design feel like revolution too.