This is a common misperception of IPFS. IPFS does not push any content onto your node or force you to host random content. It will only host content you have added or requested to be added to your node.
Someone just has to embed an illegal image or video in their webpage, and suddenly you're downloading and seeding it.
This means, there are no needless duplicates and if an IPFS node in your local network holds the data, you don't have to go to the source.
I already don't store needless duplicates, and when I decide to store something, I don't have to go back to the source after I have stored it. That's the whole point.
How is IPFS helpful?
Has IPFS made anything happen that couldn't have happened without it?
What are its biggest accomplishments, outside of its own spread?