Why Btonze Age?

[Anomalocaris]

All armored vehicles are infantry support, even today Abaris.  If it cant haul my ruck it's fucking worthless.   

Armor and mechanized infantry are complementary.   So in this sense they are muturally supporting.  

But the role of infantry dramatically changed because of tanks.   Mechanized infantry wouldn't do much of what they do but for a world made possible by tanks,  so in that sense much of modern mechanized infantry exists to support tanks.