In theory it doesn't, in practice it does. New hardware only trusts the MS first party CA out of the box (not even the 3rd party one for booting e.g. Linux distros!) and many systems do not allow removing the MS CAs from the trust store.
OTOH, once the original Microsoft-signed SecureBoot keys for both Windows and Linux became compromised in recent years, triggering the need to blacklist those keys in everyone's firmware which requires an unprecedented worldwide need for a timely firmware update only if available from the original motherboard manufacturer, along with corresponding OS updates to match, neither of which has been fully accomplished yet, there was no-one to rely on other than Microsoft to mitigate the snafu.
More than just amusing, to "quote" Ballmer: "This is by design."
It's always amusing how much people don't understand either of secure or trusted boot and start rambling about it.