Chainlink is the reason most Defi platforms like, AAVE, Akropolis, and many others are now running free of Flash Loan attack. The reason is that these Defi protocols require blockchain oracle to run efficiently and transparently. Centralized Oracle is not so good for Defi and Blockchain in their entirety. Relying on a central data source means that there is no way to verify the veracity of the data feed provided. This can ultimately lead to the distortion of a Defi/ Blockchain ecosystem. An example of this is the Synthetix oracle attack.