Germany had, in effect, developed a path dependence on East Africa. East Africa's emergence had unexpectedly given Germany, beginning in the 1880s of the last century, a vast market and source of raw materials that it could never have touched in its previous life.
Although East Africa was not a German colony, advantages such as its land area and population scale could instead bring Germany even greater economic benefits. After all, without East Africa, Germany could never have outcompeted Britain and France. Though Germany had quite a few colonies in Africa in its previous life, the returns they truly brought Germany were far less than what it earned through direct trade with a colossal nation like East Africa.
At the time, East Africa also had a public ownership economy, so profit was not its sole priority in trade with Germany. Political, cultural, geopolitical, and other factors had to be considered as well.
It so happened that Germany had already developed into a powerful industrial nation, while East Africa was still a backward agricultural country that had only recently taken shape. Thus, Germany held the upper hand in its early trade with East Africa.
That advantage slowly dissipated with time. Especially by now, East Africa had overtaken Germany in industrial development, and the trade relationship between Germany and East Africa had in fact reversed.
East African industrial goods could barely stand on the same stage as German ones, while East Africa's agricultural products, mineral resources, and other supplies were things Germany simply could not refuse. And with the arrival of war, most of Germany's civilian industries had ground to a halt, leaving it even less able to compete with East Africa.
It could be said that without the war, if this development continued, Germany and East Africa were bound to fall