[dylan604]

WTF is this nonsense? The OS updated deleted files that it had no business deleting. It's my computer. If I want to put files in the Apple approved locations or if I want to put files in / or even if I wanted to put files in C:\, it's none of Apple's damn business. If placing files in / is a security threat, then I'd suggest your not doing security right.

[SAI_Peregrinus]

SIP is Apple's documented way of reserving certain paths to be under OS control. You can disable it to modify reserved paths, but they make no guarantees about such modifications continuing to work across OS updates. If you want files the OS won't touch, keep them out of OS-reserved paths. If you want full control of all files on your machine, a managed OS like MacOS is not for you.