just a hypothesis: Tracked vehicles do not scale as well as wheeled ones (the chain has to withstand more force, has to have more weight to become stronger …)

Like expanding Guantanamo by clearing more rainforest? /s

thank you for adding more sources! I am also interested in this. They stacked 7 layers on top of each other. Alternating layer patterns (similar to a brick wall stacked alternating overlap) to prevent gas escape seems logical to me.

Also German-empire had unreliable access to colonies that produced rubber or cotton during ww1. So they used cow gut as a rubber-balloon replacement.

Layers where sewn in secret alternating patterns to make it airtight.