eh, its true if you want it to be signed by microsoft, which some projects have forked out for, buut it was put into the spec for x86_64 systems that users can replace the keys. so you can make your own keys, and if you want to dual boot add microsoft’s keys to the ok to boot list.
one of the signed projects is a shim that lets you approve whatever you want more or less; pretty much everything that talks about MOK refers back to this shim. many distributions use this shim