A basic security problem is figuring out who you can trust. You often need to trust something by default (hence root CAs in operating systems and such), or you need to have a mechanism for building trust (e.g. networks of trust such as sharing GPG keys).
And unfortunately we have seen plenty of examples of how screwed-up a default-trust scheme can become. Laptop vendors have abused their root-CA authority multiple times now, in recent memory. You don’t want the keys to the kingdom in anyone’s hands.
Besides, no matter how many assurances you give me today, I have no idea how careful you are when hiring people or how well you secure your Magic Keys. In the end, they get out in the open. This is why you can’t allow for even a single hole in the system.
And unfortunately we have seen plenty of examples of how screwed-up a default-trust scheme can become. Laptop vendors have abused their root-CA authority multiple times now, in recent memory. You don’t want the keys to the kingdom in anyone’s hands.
Besides, no matter how many assurances you give me today, I have no idea how careful you are when hiring people or how well you secure your Magic Keys. In the end, they get out in the open. This is why you can’t allow for even a single hole in the system.