I explained why I think it does provide a benefit even in a datacenter:

"Even if you just stick the key in the server's TPM without any sealing, an encrypted disk makes it much easier to deal with e.g. drive returns (for warranty or fault analysis) or disposal."

Would you resell usable drives that you no longer want to use (e.g. because they're too small or your needs changed more towards SSDs) if unencrypted data was written to them at some point?

How much effort would you put into making sure that no broken drive that can't be wiped leaves the datacenter without shredding?

Any process you put in place will have gaps - e.g. through human error or malicious acts - and this provides pretty solid protection against that.