The answers giver are good, however they also forgot the simple fact that it is simply more valuable (for most servers) to re-purpose compromised servers to be

The answers giver are good, however they also forgot the simple fact that it is simply more valuable (for most servers) to re-purpose compromised servers to be C2C or spam if it's an SMTP server than locking them up and doing (essentially) nothing with the data. The fact that datacenter PCs are essentially "cattle" PCs means that encryption is redundant - you can still get the data that you want and threaten companies the same.