theres good books on linking and loading but figuring out how the toolchains really work (gcc, ld etc.) can definitely be a pain. the tools.do provide all you need for it but you need to find out how to extract that from them. also a l9t is dependent on your knowledge about platform, abi, filetypes etc. etc. so reading specifications for those also helps to decypher meaning of possible commands, link files etc.

why its mostly skipped is i think because most platforms that provide the tools will try to also provide sane defaults for this stuff, so you rarely need it. you dont need to invoke LD if GCC can do it for you etc.