Customers often want to upgrade the processors in their servers.
Someone bought some Dell servers with 32-core processors. They upgrade to 64-core processors and have the old 32-core processors. You'd like to buy them to upgrade your servers which have 16-core processors. Sorry, even though the chips are otherwise completely identical, theirs came from a Dell and you have a Lenovo. But hey, you can buy the processors directly from Lenovo for only three times as much money.
The point of locking the CPU to a specific vendor is to reduce the trusted user base in the cloud.
Currently you have to trust AMD, the Vendor, and the data center with your data.
The goal of verification of the firmware at such a low level is to eliminate tampering by the data center.
Having another feature like SEV (encrypted memory) combined with this lets you create a secure remote box that is fully encrypted at a very early stage in the boot process.
This reduces the chance of a malicious entity at a data center from tamping with the firmware to exfiltrate your keys.
Other people here are just ignorant and think it's being done purely for profit with no benefit to the end user.
By ending the fundamental right of ownership itself, the vendor ensures no one can resell stuff and lower the value of what they "sell". It has little to nothing to do with actual security, but instead pure greed.
