Imagine the blockchain as a tamper resistant database.
You interact with it per transactions that are signed and the log is signed as well. The method of hashing hashes (blocks) and chaining them is used for making it resistant to manipulation.
In a traditional system an attacker would be able manipulate the database and the transaction log more or less easily. For a blockchain it would be very hard to manipulate this because you would have to change the history and all following blocks. Therefore the computation time will rise very high and is therefore consider more safe.
Another point is that you have trustless content of the blockchain because everything is signed and is decentralized because everyone is looking at the same state. This is also better for availability.
For EOS.IO it is kind of special because it also offers to not only store data in the network, but also use the computation power of the network which you can rent.
Nevertheless computing this needs more computation time and is therefore slower and more expensive.
- tamper resistant
- decentralized + availability
- use data storage and computation power of the network