The reason that 'systemd' is the ball of mud it is that Linux being just a kernel does not provide the basics for systemd to build on so it has to provide them itself.
The main service management-related components of systemd very much exploit the Linux kernel's facilities, so your claim is completely incorrect.
The broader tools that systemd also provides (stub DNS/LLMNR resolution, network management [DHCP, PPP...], container registration, message bus introspection and library, event loop library, EFI stub loader, device and mount management, hardware database, TTYs, NSS plugins, session and seat management, SNTP client, time/date control, dynamic configuration population, etc.) exist mostly for philosophical reasons of being a one true toolkit/middleware that sits between GNU and Linux.
The reason that 'systemd' is the ball of mud it is that Linux being just a kernel does not provide the basics for systemd to build on so it has to provide them itself.