My understanding was that you can put this in any other motherboard with the same signing key. Presuming the intent her is that every single machine would have

My understanding was that you can put this in any other motherboard with the same signing key. Presuming the intent her is that every single machine would have to have a different signing key. If this was the case, then yes, security seems to be the reason. However, and I may have misunderstood this so please do correct me if I have, based on the article, it seems for certain vendors, they share the same signing key with multiple machines (presuming whole lines), in which case this certainly seems to be about vendor lock-in from the vendor side.