Hi spookypooky!

Even though it's for bitcoin, its still very applicable to STEEM!
If I had to summarize it in a few sentences, nodes create the network for STEEM, with no nodes, no transactions/information could ever be relayed from one user to another. Just like with torrents, seeders = nodes. No seeders = no one benefits. More nodes = more robust network.. Here's an in-depth explanation to nodes: https://en.bitcoin.it/wiki/Full_node