Looking back, it's unfortunate that Unix authors offered piping of input and output streams, but did not extend that to arbitrary number of streams, making process arguments just a list of streams (with some shorthand form for constants to type in command line, and universal grammar). We could have been used to programs that react to multiple inputs or produce multiple outputs.
It is obvious that it made sense in the '70s to just copy the call string to some free chunk of memory in the system record for the starting process, and let it parse those bytes in any way it wants, but, as a result, we can't just switch from list of arguments to arbitrary stream without rewriting the program. In that sense, argument strings are themselves a workaround, a quick hack which gave birth to ad-hoc serialisation rules, multi-level escaping chains, lines that are “too long” for this random system or for that random system, etc.
They did though - file handles are inherited by child processes which allows you to pass one end of a pipe and then feed things into the other end. E.g. make uses this to communicate between recursive invocations for concurrency control.
Most linkers have workarounds, I think you can write the paths separated by newlines to a file and make the linker read object file paths from that file. But it would be nice if such workarounds were unnecessary.