Except you don't see this in the Roman Empire. If anything, the economic sophistication of their european opponents steadily
declined, making war a more appealing option than trade for them.
And in warfare itself, with the exception of the Sassanids and the civil wars, the Romans did not face armies that had adapted their tactics. Rather, the longstanding issue of inferior roman cavalry in both quantitative and qualitative terms and the decline in quality of their infantry legions/ reliance on auxiliaries made them far more vulnerable to concentrations of heavy cavalry, horse archers, and non-pitched battles. For a variety of factors the averagesquality of western Roman armament and training consistently declined from about 200 AD on, which is the opposite of what you're saying.
Decadence is a politically loaded and over-determined word and there are myriad factors contributing to the fall of the Roman empire in the west, but the thesis that the germanic, central asian and gaulic tribes had successfully adopted Roman administrative and logistical forms has no historical basis. I get that it's supposed to be a cute metaphor for tech companies and market-wide adoption of an innovation, but if a metaphor is advancing a novel thesis that's empirically false, it's not a good metaphor.