What is the point of Decentralized storage

Question

I seriously didn't get the point of decentralized storage, 

Servers are providing free cheaper services to store cloud data and storj sia or IPFS(using hastable a little different from other 2) provides data storage where data is storing in multiple nodes(4 to 5 or more copies for better retrievability) in multiple parts, Is this not storage wasting?

On servers data might be stored in 1 or 2 copies as Backup but 4,5 or more copies in the name of Blockchain where miners are not ever getting paid in good amount  for how much free storage units setting on rent and may leave it with destroying whole data that stored on there node and also no retrievability guarantee,

Is this a durable concept? Please tell your review...

Answer 1

In many cases, you are right – there's no need for the entire data to be stored on every node, but there is value in a hash of that data being replicated across the network, to create a tamper-proof record. It depends on what kind of retrievability guarantee you want, and how large the data is. Off-chain stream items, shortly to be available in MultiChain 2.0 alpha, will let you choose to do things either way.