Here's why:
* Wasteful and Inefficient: The construction of the station is depicted as a massive undertaking, consuming vast resources and manpower. Yet, its purpose is ultimately unclear and seemingly pointless. Marlow observes that the station is largely neglected, its buildings crumbling, and its purpose lost in the jungle's encroachment. The immense effort invested is a stark symbol of the colonial project's ineffectiveness and ultimately its own self-destruction.
* Symbol of Colonial Arrogance: The station represents the colonialists' attempt to impose their will and systems on a foreign environment. However, the jungle, a metaphor for the unyielding power of nature, ultimately triumphs. The station's decay reflects the futility of trying to control and dominate a place that is ultimately beyond their grasp.
* Exploitation and Suffering: The construction of the station comes at a high human cost. The natives are exploited as labor, forced to work under harsh conditions with little regard for their well-being. This highlights the brutality and dehumanizing aspects of colonial exploitation, further highlighting the ineffectiveness of the project.
Marlow's observations of the inner station serve as a microcosm of the larger colonial endeavor in Africa. It embodies the waste, the exploitation, and the ultimate failure of imposing European systems on a land and its people, emphasizing the ineffectiveness of the colonial project.