The hierarchical structure of management is common to multiple big and small organizations. They look like pyramids with CEOs at the top of it. Every person in the organization subordinates to someone else, therefore, every worker in the middle of the pyramid has their bosses and subordinates. Non-profits do not stay aside. Hierarchical structure helps them maintain a status quo, which brings them stability. Today many organizations consider it a weakness, but environmental organizations take status quo as an essential feature to prove their viability.
Having a virtuous CEO, non-profits get more chances for funding. Conservation groups usually struggle to find the resources they need, and they cannot attract donors if they look too risky to potential investors. A flat structure brings disorganization, especially when applied to a big company. Being very innovative is good for small startups, but organizations collecting big money for conservation of wildlife have to have a clear management and flawless reputation. A hierarchical management suits best such purpose.
Apparently, conservation organizations do their best to remain attractive to investors. But preserving the wildlife depends on more factors such as legislation, local involvement, poor planning and vague goals put by conservation groups. They often need common efforts to take actions but eventually cannot get them. We all live in the same environment and have our own ambitions to what nature can bring us. Conservation organizations, in their turn, do not have a superpower to stop legislative negligence, industrial abuse, and illegal actions of individuals. Most likely, the type of organization has nothing to do with it.