Change the word mining to computing, and it’s more intuitive. A network of nodes compute stuff together, making data available across the network. It’s like as

Change the word mining to computing, and it’s more intuitive. A network of nodes compute stuff together, making data available across the network. It’s like asking why is a distributed network valuable. During the process of computing, the network validates stuff about the data, guaranteeing it properties, so that people can rely on it to a certain degree when reading from and writing to it.