This was true in Windows 8 times, but with Windows 10 the requirement to be able to turn off Secure Boot vanished: https://arstechnica.com/information-technology/2015/03/windo...

The whole story around Secure Boot could be understood (even without a tinfoil hat) as a part of a slippery slope to lock out alternative OSes, highly recommended post: https://www.phoronix.com/forums/forum/phoronix/general-discu...