What exactly is the lack of transparency in systemd?

What exactly is the lack of transparency in systemd? Is the claim that systemd log files are not transparent just because they are binary files or because the binary files are difficult to parse and understand or because they are actually undocumented? The same question applies to the configuration files which I guess are replacing scripts. If I were to go and try to write a parser using, say, lex/awk to read the files would I find that a 3 hour job, or would it take weeks?