Basically, I’m just curious about the history.
When was the first linker written? What was the rationale at the time? E.g. was multi-language development an issue? What platform did it target? What languages and compilers were supported? What interesting stages did they evolve through?
According to Linkers and Loaders by John Levine the concept, at least, was around in 1947, with significant development of the modern linkage editor by the 1960s. They are used to allow the reuse of libraries of modules developed separately by various programs that need them. I suggest reading the text (linked above from Google book search) for more information.