Win 10 is outdated. And this blog is for IT professionals I guess, having to manage hundreds or thousands of devices. So, if you decide to go with that old hardware, only capable of running Win 10, and the certificates won't be installed automatically, you just do nothing.
If the device really won't be able to boot someday, you just deactivat Secure Boot in Bios. That's it.
MS can't trigger an automatic update on really every device, because this could lead to boot errors, if the device isn't capable of running it.
In my understanding, they slowly build up a database of more and more device type, where they are highly confident, no problems occur when installing that new certificates. If your device falls in that high confidence category, it installs the certificates automatically.