The point is not decentralization in of itself, but what it enables. Written knowledge is massively entangled with other ideas, written for specific audiences, assuming a level of background.
If you are an individual with a health condition trying to learn, how can you read and understand the source research papers without getting a degree in molecular biology? Its okay to have a centralized repository of knowledge catered for a specific audience. What decentralization enables is to take these research papers, with massively condensed ideas and pry out the assumptions contained for audiences that aren't familiar. Even if the conversation isn't suitable for MedSchlr itself, the same information can be taken to another community relay for discussion to elaborate on the fine grained details that might not be suitable for a medical knowledge base.