The Linux, Unix, and POSIX manual pages document the Linux, Unix, and POSIX systems. A system is a set of things (in these cases, many things) that work together. They do not just document the kernel part of the operating system. They document commands for users, commands for programmers, utilities for system administrators, routines in libraries for programs, system calls for making requests of the operating system, and other features of the entire system.
When the manual pages were started, there was no C standard from ANSI, ISO, or IEC, and so it would not have been possible to defer to those organizations. Further, many of the routines provided by these systems specify behaviors beyond those of the same routines in the C standard library.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…